The author wanted to confirm whether or not Necator americanus is communicated through oral membranes and, should this be the case, whether the infection is influenced by the time length of contact with oral membranes. Experiments were conducted to observe whether a larvae can become Necator americanus in the human body by contact with oral membranes. The following results were obtained:
I 1st experiment to apply larvae to oral membranes for 300 seconds.
1) Infection was observed in four out of five volunteers.
2) The four volunteers were free of apparent subjective symptoms in the time period up to expelling.
3) As to objective symptoms, eosinophilie increased in the blood picture of the four volunteers infected.
4) For the four volunteers infected, ova and larvae were found within 58 through 108 days after infection.
5) Necator americanus was obtained from the four volunteers by expelling; 24, 21, 3 and 7 respectively.
6) The rate of collected Necator americanus to the larvae applied was 13.8%, 14.7%, 0, 2% and 3.3%.
II The larvae of N. a. were applied to oral membranes for 90 seconds in 2nd experiment.
1) No infection was observed in all four volunteers.
2) No one complained of subjective symptoms in the time period up to expelling.
3) Change in the blood picture was not observed for all four cases.
4) No Necator americanus could be collected by expelling in all four cases.

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The objective of the present research is to examine the relationship between drivers' work time and conduct of driving. Research has been confined to the behavior of the drivers, the operation of the vehicle as well as the fatigue problem.
Results of questionaires distributed among 307 drivers are as follows:
(1) Operation of the vehicle (clutching, braking, accelerating, steering, gear shifting) were found to be independent of the drivers' work time.
(2) There appeared to be a close relationship between fatigue and frequent accidents on the 8.1∼hr/day driving. In addition there was a traffic accident tendency attributed to drowsiness of drivers under the 0∼3.0hr/day driving.
(3) Many traffic accidents occured on 12-14, 14-16 o'clock, but these were independent from working time.
(4) Values (traffic accident frequency/drivers' work time) are presumed to be a better index than the frequencies themselves in order to correctly evaluate the survey of the specific relation between drivers' work time and conduct of driving.

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Botulism is a food poisoning which is caused by taking in nerve poison produced by Cl. botulinum which multiplies in foodstuffs.
In Japan, since 1951 occurrence has been mainly in Hokkaido and Tohoku (northern part of Honshu) districts. Up until the present time 63 outbreaks have been reported and 93 people out of 359 patients died.
Toxin produced by Cl. botulinum is classified into 6 different types: A, B, C, D, E and F according to their immunological nature. Of these 6 types of toxin, types A, B, E and F are the cause of poisoning in human beings whereas types C and D affect cattle and fowl.
Botulism in Japan is mainly attributable to fermented preserved foods such as “IZUSHI” and “KIRIKOMI” which utilize raw fish as their component. But it should be mentioned that type B poisoning, which occurred in Miyazaki Prefecture in 1969, is thought to have been caused by imported caviare, 21 people were affected, 3 died.
Therefore, while only type B episodes have been previously reported in Japan, the discovery of types A and B strains in the soil of Tohoku district should make it clear that outbreaks due to other types are now possible. The possibility seems to be higher since a poisoning from imported food has occurred.
The study of botulism in Japan has been conducted mainly on type E which has frequently broken out. The geographical distribution of type E organisms in the soil, the multiplication in “IZUSHI”, the conditions of toxin production, the chemical nature of the toxin, and its remedy using antitoxic serum have all been studied. But the author has taken up the following problems broadly not only on type E toxin but also other types of toxin due to the above mentioned reasons.
Why is botulinus toxin not affected by the proteolytic enzymes in the digestive tract? Though the effect of proteolytic enzymes on the toxin in the digestive tract is a very urgent problem, no unanimous conclusion has been reached.
In other words, no report on the study of the effect of proteolytic enzymes of all the six toxins, already known to us, under the same conditions has yet been published. Bearing this in mind, the author made a study on the effect of various proteolytic enzymes using crude botulinus toxins (cultural super-mates) under simulated natural conditions.
The results obtained are as follows:
(1) With type A, strain 190, type B, strain Lamanna, and type F, strain Denmark which belong to the Proteolytic Group, a remarkable attenuation of their toxicity was observed on both acid and alkaline sides. But inactivation of the toxins due to enzymes was not particularly notable.
(2) With toxin type C, strain Stockholm and type D, strain 1873 which belong to the Non-Proteolytic Group, the effects of fluctuation of PH and the action of various types of enzymes were comparatively slight.
(3) With type B, strain QC, type E, strain Iwanai and type F, strain 70 F which belong to the Non-Proteolytic Group, activation of the toxins was observed by treating them with trypsin at PH 6.0. Generally speaking, except for type F, effects of fluctuation of PH and of various enzymes were slight.
(4) When botulinus toxin is taken orally the toxin changes its toxicity in varying degrees by fluctuation of PH in the stomach and the intestinal tract or by action of digestive enzymes, and it is presumed that a considerable amount of active toxin remains in the digestive tract.

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The particular phenomenon observed in the trachea of the germfree animals exposed to the air containing silica particles was the invasion of the particles into the epithelial cells and the subepithelial layers. In conventional animals, no invasion was noticed. Sulfur dioxide gas of 40ppm impeded preventive functions of mucous membrane of the animals both in germfree and conventional, involved in removing the extraneous substances and bacteria. Basic pathogenic changes in the lungs of germfree guinea pigs under the influence of SO₂ gas or of Staphylococcus aureus 209p infection were interstitial inflammation in the circumferential alveolar septa around the bronchioles and capillaris. Changes in the lungs of germfree animals affected by SO₂ gas with a combination of bacteria were modified by superimposed brochopneumonia following numerical changes of bacteria in the lungs.

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