A new technique is described by which the existence of the evoked potential of waked human brain to acoustic stimulation is detectable from the background activities with ease and security.
In this teconique, to the recorded numerous waves under the same condition, nhe base-line is given to each suitable position, and measuremeut of the distance from the base-line to the progress of the curves on each point is made compounding all waves at the same starting point of the stimuli.
By means of this management, the amplitude of the evoked potential is accumulated, as each response has the same latent period, phase and duration, and the form of the response be-comes to be recognized much more easily.

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The accuracy and speed are the important factors in group hearing test for school children.but also they are contradictory each other.
The auther presented a new method of screening test for school children with two test tones of 1000 cps and 4000cps at a level of 20 db., which is considered as solution for this contradiction in group hearing test. Five thousand three hundred and eighty-two of school children were tested by this method during 1955-1957.
These results were studied by statistical analysis.
Test tone of 1000 cps at a level of 20 db. revealed the hearing loss more than 25 db. in 84.5% of the ears, and the hearing loss more than 30 db in 96.2 0 on audiogram. But in 1.5 6 of healthy ears with the hearing loss less than 20 db at 1000 cps incorrect results were obtained.
Test tone of 4000 cps at a level of 20 db. revealed the hearing loss more than 25 db in 77.5% of ears, and the hearing loss more than 30db. in 1000 of the ears on audiogram. In 0.3% of healthy ears with the hearing loss less than 20db. at 4000 cps, incorrect results were obtained.
Speed to perform the test was about from 80 to 150 children per one hour.
This screening test was possible to examine even younger children such as first and second graders, and showed high reliability.
This screening teat may be considered to overcome three difficulties in pure tone screening test for the group of children, which were speed of test, need of sound-proof room and exhaution of those to perform the test and tested subjects.
This screening test was proved as having high reliability and high speed of test, when this test was performed under quiet circumstance.

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The stenosis of Eustachian tube was studied histopathologically. Since there is no change. in the finding of retraction of the ear drum after death, from the condition of the ear drum in post mortum examination, the presence of the tubal stenosis was presumed.
In this study the serial section of the temporal bone from 11 cases including the one case with the tubal stenosis with the retraction of the ear drum and 3 cases without retraction, were microscopically examined.
The results obtained were as follows:
1) The degeneration and the falling out of the epithelium were observed in many cases with retraction.
2) There was no relation between the amount of goblet cells and the degree of the retraction of the drum.
3) There was no difference in number of glands in those with retracted drums and those without retraction of ear drums.
4) The exudate was seen commonly in the portion of the isthmus.
5) The developement of lymphoid tissue was prominent in the cases with the retraction of the ear drum.
6) The infiltration of polymorphnuclear leucocytes in the mucosa of tube was more prevalent in the cases with retraction than in the cases without retraction, and these leucocytes were found to be wandering into the epithelium.
7) The chronic inflammatory reaction of the mucous membrane in the retracted cases appeared to be more prominent than in the un-retracted cases.
8) The inflammation of the mucosa in the tympanum was not so serious as that of tubal portion.
9) Acute catarrhal inflammation, in two cases of a baby and an infant, was observed in the mucosa of tympanum.
10) The tubal lumen was partially narrowed in only one cases, but no cicatricial obstraction was found in any cases.
11) In one case, the marked prominence of tubal wall by the lymph, follicles was found in the pharyngeal portion, but in generally the lymphoid tissue in the mucosa of tube, was poorly developed.
12) The author stressed that inflammatory changes of the tubal mucosa and the accumulation of inflammatory exudate in tubal lumen, were the important causes of the tubal stenosis, and the prevention and treatment of tubal stenosis would be accomplished by keeping the normal respiratory air current in the nasal and nasopharyngeal cavities.

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It is generally- recognized that the extent of pneumatization of the mastoid cells may be genetically determined. On the other hand, otitis in infancy has been considered an inportant factor associated with underdeveloped mastoid cells. The author and T. Goto do not agree with this opinion and have believed that the development of the mastoid cells may be genetically determined.
Recently T. Goto and S. Shibata have reported that there is a marked fibrosis in the lungs of skin divers and limited development of the mastoid cells. From these results they suspected that pressure might have some influence on the extent of pneumatization of the pneumatic cavities, the lungs, accessory sinuses and mastoid cells.
The author has planned to study experimentally the effect of pressure upon the mastoid cells.For this experiment he constructed a pressure tank, in which constant pressure could be maintained at 3 atmospheres or at a pressure of 2/5 of an atmosphere. The oxygen was insufflated into the tank under constant pressure.
The animals used for this experiment were young chickens 7 days old at the start of the experiment. The chicken has well-developed mastoid cells and its mastoid cells develope very quickly. The experiment was carried out on the two main groups, namely the high pressure group and the low pressure group. Chickens in each of the groups were placed in the tank for 2 hours daily. In each of these groups the observation was made at the end of 30 and 60 days on 15 chickens in each subgroup. During these experiments chickens have not shown any gross changes. The development of the chickens was not delayed compared with the control chickens.But the mastoid cells of each group were markedly underdeneloped. The septae of the air cells were thickend and the lumen of the-cells were decreased in size. The bight of the linning epithelial cells was increased and the subepithelial tissue was fibrous and thick. Residual cartilage tisstue was found. The microscopic appearance of the air cells in chickens exposed for 60 days to high and low pressures are similar. The normal process of development, in which leucocytes infiltrate the subepithelial tissue, macropgages cause bony resorption, and the epithelium proliferates causing an increase in pneumatization, is delayed.
These findings indicate a delay in the development of the mastoid cells. The findings in the mastoid cells of chickens in the two groups were similar, whether they exposed to positive pressures or negative pressures. The animals exposed for the longer time period (60 days) revealed only a slightly increased limitation in the development of the development of the mastoid cells than seen at the end of 30 days.

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The author severed the VIII nerve of dogs within the cranium, and observed the influence upon the ear labyrinth pursuing the course of the clinical symptoms and histological study of inner ear degenerations, and the following conclusions were mode:
1) Vestibular symptoms were the most remarkable immediately after the seneranse of the VIIInerve and gradually recovered by the central compensation leaving no sequellae.
2) Post-rotatory nystagmus by Bfarfany's method was larger in jerk numbers I can find more big, numbers of nystagmus duration and jerk numbers and longer in duration in the ill side rotation.than the sound side rotation.
3) Cochlear neove, of the the sensory nerves, showed peripheral degeneration which is against to the Waller's low.
4) Cochlear nerve degeneration started at the point of severance and progressed centrifugally extending from the nerve stamm fibres to the spiral ganglia and still further to the peripheral nonmedulated nerve fibres.
5) Vestivular nerve fibers also showed pheripheral degeneration. There the cutting lead to the peripheral degeneration in the vestibular fibre was a tendency of temporary delay of the degeneration at vestibular ganglia.
6) There was no relation between the secondary degeneration of the nerve tissue and that of the endorgans of the nerve but a light atrophy of the endorgans was abserved after the long.period.
7) The degeneration of the endorgans of the nerve was caused by circulatory disturbance.
8) The inner ear disorders start, from the nerve tissue orfrom the endorgans in accordance with the causing factor.

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The behavior of the auditory fatigue can be divided into two groups: per-stimulatory and poststimulatory. In this paper per-stimulatory fatigue was determined by bilateral loudness balance test.During a continuous stimulation of 5 minutes at 90db sensation levels in 1000cps on one ear, a pure tone of short impulse in 1000cps was applied on the other ear 15 seconds and 30 seconds after the stimulation and thereafter every 30 seconds. By adjusting a balancing tone to a fatiguing tone, the loudness balance of sensation in both ears was obtained in every impulse.
In the testing of 100 persons with normal hearing, auditory fatigue developed abruptly in almost all individuals within first 15 seconds, and maintained a parallel equilibrium in 2 to 4 minutes at the dial ranging from 85 to 15db in the balancing ear. The distribution of the final level of balancing.tone seemed to correspond to the normal distribution with central peak around 60 to 45db. The auditory fatigue of the individual was always constant, and was not affected even by the condition of menstruation or general malaise, expect in cases of extremely severe physical fatigue such as playing mah-jong or heavy work through all the night.
The level shift of baeancing tone, namely the auditory fatigue, increased after the administration, of Priscol (1% Icc) in all 10 cases, and after Pilocarpin (1% 0.5cc) in 8 cases out of 10 cases, whereas decreased after the injection of Atropin (0.05% 1cc) in 5 cases out of 10 cases. The level was not affected by the injection of Nor-adrenalin (0.10 lcc). The auditory fatigue decreased following the intravenous injection of 7% sodium bicarbonate solution in 50cc dosis in 9 cases out of 12 cases.

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1. Experiments were done on the development and recovery of fatigue of the inner ear of guinea pig. Continuous pure tone stimuli were given and the change in the cochlear microphonics was traced and recorded from different parts of cochlea using an intra-cochlear microelectrode.
2. Fatigue which was not observed by relatively low tone stimuli with the electrode placed around the round window or into the basal turn, observed in cases of recording from the second or the third turn.3. The region of cochlea which showed fatigue most remarkably was dependent on the frequency of sound applied, being the third turn for 125, 250 and 500cps., the second turn for 1000 and 2000cps, the basal turn for 4000cps. respectively.
4. The intensity of the stimulus to induce the fatigue in one minute was dependent on the frequency, being 115db_??_120db at 125cps., 110db_??_115db at 250cps., 107db_??_112db at 500cps., 96db_??_101.db at 1000cps., 104db_??_109db at 2000cps. and 96db at 4000cps. (sound pressure level) respectively, and no fatigue was recognized by the stimuli below this level even when the rstimuli were' given continuously for five minutes.
5. Development of the fatigue was influenced by intensity of the stimulir ather than duration of the stimuli, while in its recovery process the reverse relationship was observed.
6. The region of cochlea which was most responsive for certain pure tone stimuli was found to coincide with the region which showed sign of fatigue most easily for the same tone stimuli.

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The author obtained corti's organ of guinea pigs and observed each cell-group from tangential direction using Feulgen reaction and M.G.P. stains.
The results were as follows:-
1st. Chapter
1) 2% Formalin was the most favorable for the fixation of corti's organ.
2) Chromatin granules in cell nuclei showed three formulas of metabolic phase.
3) Concerning size of outer hair cells, the 1st raw was smaller than the 2nd and the 3rd raw, and was easily injured.
4) Deiter's and Hensen's cells showed relative resistance to physical and chemical stimuli.2nd Chapter
1) By D.H.S.M. injection, corti's organ showed functional disorder in the early stage. When the dosage was increased, the damage of the cells and injuries of head plate was observed.
The changes were remarkable in the 1st and the 2nd winding.
2) When Vitamin B1 was injected togather, these changes were less remarkable and recovered more rapidly.
3) Deiter's cells were More resistant to the high dose of D.H.S.M., but once the functional dis order developed, recovery was slower than the hair cells. This might be one of the factor in the delay of the recovery the auditory disorders caused by D.H.S.M.
3rd Chapter
1) Sound stimulation produced more apparent changes in the 1st raw of outer hair cells than the 2nd and the 3rd raw of the cells.
2) Stimulation by impulse tone produced the changes in outer hair cells about 2 min. after the stimulation but recovered within 2_??_4 hours.
3) By investigation of the cell metabolism in camera silenta, outer hair cells were thought to show restitution.phase in about 2 hours and extrusion-phase in 8 hours.
4) Thus first 4_??_8 hours after the stimutation are most important for the recovery from early injuries by sound stimulation, and during this period, release from sound stimuli and medication are recommended.

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Many experimental results on vibration of the vocal cords have been reported by previous investigators, Helmholtz, J. Muller, Ewald and others.
Various materials were used as models, that is to say, gum, Larynx of the human corpse and femur muscles of the Rana nigromaculata.
In vibration of the vocal cord, its lateral motion can be easily recognized through direct or indirect laryngoscopy, but its up-and-down motion is difficult to observe.
Motion of the vocal cords are so complicated in its nature that it requires an observation by themodel experiment to analyse and verify its action.
Gutzmann, Trendelenburg et. al. mention that montion of the vocal cord has a very complicated nature. It is understand that the vocal cord makes lateral and up-and-down movements by the expirotory air pressure in the trachea, while the automatic motion of the vocal muscles and its elasticity cause changes in the shape of the vocal cord while vibration.
In order to study the points that are impossible to observe in the human vocal cords, I made an experimental study by the model vocal cords using the femur muscles of the Rana nigrimaculata.
The characteristics of this model experiment was that the whole femur muscles was used as nerve muscle specimen instead of using the partially excised muscle.
Therefore, experiment of the muscle model having automatic constractility of the muscles became possible by stimulation of the ishiadicus nerve.
The results were as follows: ......
1) The model vocal cords underwent complex motion of combination of horizontal and up-and down movement while vibration.
2) The shape of the vocal cords smoothly changed periodically while vibration.
3) Relationships between air pressure of blowing the models, tenssion of the muscle, and frequencies of sounds produced by the vocal cords were studied.
4) Characterics of the primary tone produced by the model vocal cords were studied by means of +sonagraph.

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The authors reported a case of improved bone conduction in a middle freqency range after removal of cholesteatoma in external auditory canal. After removal of cholesteatoma bone conduction improved about 15db at 3000Hz. and 4000Hz.
Reduction of bone conduction threshold was studied, by the instillation of about ice of fluid into the external auditory canal. The reduction was about 2.5db at 4000Hz. that is significant from statistical testings. Such a reduction was considered to suggest that the change of external auditory canal contributed to bone conduction.

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Twenty-nine maxillary sinuses from fifteen adult cadavers were selected and the relation between the antral floors and the apecies of the root of the molar teeth was investigated.
The distance between the. antral floors and the root-apecies of the molar teeth was measuredin 152 cases; in 94 cases, the measurements were in a range of 0-4 mm. and in 58 cases, measurements were in a.range of 4-16 mm.
Particulary, four apecies were- exposed in the sinus, and one palatinal root-apex of an upper first molar tooth was located in the depth of 20 mm. from the antral floor.
The root of the upper molar tooth divide into two portions namely buccal root and palatinal root.
The distance from buccal root-apex to antral floor and that from palatinal root-apex to antral floor was almost equal. In 49 cases out of 53 cases (92.5%), the difference of both measurements was within 1 mm.
The most accurate roentgenological measurement of the distance between the buccal root.apex and the antral floor was obtained with the main axis of X-ray in an angle of 30- to the occlusion plane.
It was found that when X-ray shows the buccal root in contact with the antral floor and the palatinal root in cross with antral floor, anatomical examination reveals the contact of the buccal and palatinal -roots to the antral floor.

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A Case of maxillary cancer ih a twelve-year-old boy was repoted.
Histological examination revealed a basal cell carcinoma. ray irradiation, totally 3150r, was given preoperatively and radical redical resection of the maxillary bone and radical neck dissection were carried out under endotracheal anesthesia. The postoperative course had been smooth and 2 years after the operation, no recurrencc was seen.
Maxillary cancer in children under twenty years of age is very rare. In this age group only 6cases have been reported in Japan and among 1011 cases of maxillary cancers collected from the literaturs only 3 were under twenty years of age. The prognosis of these cases in general is poor.

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The author made a statistical observation in 122 cases of chronic otitis media treated by the radical mastoidectomy. Complete wound healing was seen in 62.3% of the total number cases. Among those with incomplete wound healing, the difficulty was seen in window niche in 37.0%, at the orifice of the eustachian tube in 28.2%, in hypotympanum in 23.9%, in promontorium in 8.7%, in perilabyrinth or sinodural angle in 8.7%, in retrofacial area in 6.5%, in attic 4.3% and in perisinous area in 2.2%. In 49 cases reoperated, the pathology was found to be seen in the cells and mucosa in most of the cases. In 15 cases of which numbers the result of the operation appeared to be satisfactory at first but no complete healing could be established. Microscopic examination of these cases revealed the failure of healing to be the presense of pathological mucosa that interfered with proper epidermization.
Morphologically, the pathological mucosa was classified into 9 different types. The most conspicuous change was the infolding of the mucosa and cyst formation. The cyst has also been observed beneath the epidermis where the clinical healing for a period of time had been satisfactory. It is impossible to remove the mucosa completely during the opration, nor is it possible to zation superimposing the impreventable mucous membrane which when examined microscopically will show cyst formation and air cavity, the proximal end of the eustachian tube. The pathological bone does not always interrupt the epidermization. The author could find one tympanic gland out of all cases. This one was a single tubal gland and it's blind end tended to form a cyst.

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1) The historical, gross and microscopic investigations of chronic maxillary sinusitis have been made on 84 cases with 133 sinuses, especially from the stand point of allergy.
2) The sinus mucosa is classified into three types according to Hansel's classification method by the histological observation. The results obtained are as follows:
(i) Allergic type ............... 12.0%,
(ii) Purulent type ...............24.1%,
(iii) Combined type............ 63.9%,
3) The marked edema is found mostly in the allergic and combined types, and not in' the purulent type.
4) Eosinophiles are helpful for making diagnosis of allergy although the marked infiltration has never been observed in our cases. It may by because of these allergies are of chronic type independent of seasons.
5) The increase of goblet cell may be one of the basic evidences for the discrimination of the allergic type.
6) The thickening of basement membrane is not specific for the allergy.
7) The incidence of thrombi formation is almost equal in these three types, though it is slightly higher in the allergic type.
8) The swelling of blood vessel wall is seen most frequently in the combined type, and lest freuquently in the purulent and allergic types, since it might have a' close relation to the bacterial allergy.
9) The history of allergy of the patient and his family is important for the diagnosis of the allergy.
10) The nasal polyp, the pale swelling of nasal mucous membrane and the edematous or polypoid hypertrophy of nasal mucous membrane are found most frequently in the allergic type and the combined type of maxillary sinusitis, and have fairly close relation to the allergy.
11) Whence, the diagnosis of allergic sinusitis may be made considering the above mentioned observed facts.

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Clinical and Patho-histological studies were perfomed on the arythenoids of fifty-three eses (48 mleale, 5 female) of the laryngeal cancer.

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The author tested total 381 ears with normal and impaired hearing, by means of the continuous frequency self-recording audiometry (continuous method), and evaluated the clinical significance of the audiometry in (1) the threshold test and (2) the recruitment test.
1) As the threshold test, the continuous method is not advisable in the similar sence that of the audiogram obtained by means of the ordinary manual audiometry, because in many cases there are errors in determination.
2) As the recruitment test, however, the continuous method is advisable in the similar sence that of the fixed frequency self-recording audiometry.

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