On Artificial Ovulation in the Spinous Loath. 1. Changes occurring in the ovarian eggs of the spinous loaches which were injected with frog pituitary suspension during the breeding season were observed microscopically on sections of fixed material. At 25°C the changes found in most of the eggs were as follows: Yolk granules surrounding the germinal vesicle begin to dissolve two hours after the injection. The germinal vesicle is moved towards the animal pole one hour later. At the fifth hour after the injection it disappears and all of the yolk granules contained in the egg show a tendency to become larger by fusion with neighboring ones. At that time the eggs begin to become semi-transparent. The first maturation spindle is observed in the eggs which were fixed six hours after the injection. The metaphase spindle of the second maturation division is formed one hour later. About that time ovulation begins to occur in the spinous loaches. 2. The unfertilized egg shed into water gives off the second polar body and forms the female pronucleus in the egg as the fertilized does. 3. When fragments of the ovaries of spinous loaehes are immersed in frog pituitary suspension in vitro, ovulation occurs. One of the eggs extruded from the fragments cleaved normally after insemination.
Since 1940, the author had given the hydrosol of Androsteron and Esteron to Sôgyo, Ctenopharyngodon idenus with undeveloped sexual gland and by 1949, gained the following results: 1. The sexual 'glands of males and females of C. ideilus were fully developed by giving hormones through the medium of the mouth with food processed. However the artificial fertilization was not successful. 2. The spawning season of C. idenus at Hikone in Shiga Prefecture was found to be from April to July, and during the period pearl organs appeared on the surfaces of the fins of males. 3. Judging from the fact that large C. ideiius were often captured along the shore of Lake Biwa, they seemed to come towards the shore for spawning. But, their sexual glands were far less developed than those of the fishes which were given hormones. 4. Consequently, the author concluded that it was wise and proper for the propagation of C. idenus to set free the fishes after sexual glands had fully grown as the result of hormones given in the test pond. The author wishes to express gratitude to the Education Ministery for giving a part of the Scientific Research Fund to his Project. This experiment was made possible by the co-operation of Mr. Moritô Kikuchi, former governor of Shiga Preiecture, Mr. Seizô Suzuki, head of the Shiga Prefectural Fisheries Experimental Station and his fellow officials, Mr. Kôtaro Yamanaka, Hyogo Prefectural Engineer, Dr. Tadao Satô Professor at Nagoya University and Mr. Tôji Nakamura, owner of of the Nakamura Fish Farm. The author also wish to express appreciation to Dr .Masao Migita, official of the Fisheries Experimental Station of the Agriculture and Forestry Department for his supplying materials.
With the liberation of fry and propagation of Ayu, deciding morphological characteristics between Natural Ayu and Pond-cultured Ayu is attached great importance to estimate the commercial value and establish the protection and conservation of Ayu. And the difference of growth degree in living place form an interesting data for our study. The measuring position is illustrated in Fig. 1. The measurement value is respectively compared with the ratio to the body length, and showing the following formula to 1w (average value of distance between each growth ring), I (scale length-distance from the nucleus to the edge of apical' field) and L (body length), scale's circuli are compared with everybody: 1W/1×L×100=K These results will be summarised as follows: (I) The sexual dimorphism (The measuring result is illustrated in Table 2 & 3). a) Male's body breadth is wider. Female's shape is asymmetric in maturity. b) Male's Dorsal, Anal and Pectral fins are longer., There is no dissimilarity between male's Caudal fin and female's one. c) Dorsal fin of male is situated forwards, and Anal fin lies backwards. d) Male's head height is higher, and its length is shorter. e) Male's fusiform speck situated in the upper part of pectal fin lies forwards. f) Pearl organ, secondary sexual characteristics, is generally appeared in male, but the coefficient of the apparition in female is only 14.2% (II) The dimorphism in respect of circumstantial difference (the measuring result is illustrated in Table 4 & 5). a) Body breadth of pond-cultured Ayu is wider. I conceive this is rather attributable to the animal bait than the water current. b) Body heirht of female natural Alm is apt to be hirher. c) Ventral and Anal fins of female pond-cultured Ayu are severally situated forwards. d) The position of pond-cultured Ayu's Anal fin is higher. e) Head length of male natural Ayu is longer. f) The speck of female pond-cultured Ayu lies forwards. (III) The difference of scale's circuli (illustrated in Fig. 2 & Table 6). The scale's coefficient of natural Ayu is smaller than the pond-cultured Ayu's. This is due to the propriety of growth, I consider. We can disceiminate the natural from the pond-cultured: If body length is up to 18 cm., K is 50, not exceeding 55 if it is up to 24 cm. And also it is possible that finding K, we can suggest the limnological factors of surroundings where Ayu lives or the skill of pond-culture technique.
The present species was erected in 1909 by Tanaka under the name of Alepo-somus watasei, based on 2 specimens measuring 235 and 265 mm respectively in standard length, and since no other record has been made. The present single specimen measuring 177.8 mm in standard length, which was taken from Numazu in summer, 1938 and was lost off by the fire, does not agree well with the original description as will be seen later on. D. 19 ; A. 17 ; P. 8; V. 7; branchiostegal rays 6 ; gill-rakers on first arch 8+19=27. Head 4.39 in standard length ; depth 5.42 ; distance from tip of snout to the origin of the dorsal 1.48 ; same from tip of lower jaw to the insertion of ventral 1.85. Snout 5.26 in head ; eye 3.52 ; membranous interorbital space 4.66 ; bony interorbital space 6.04 ; maxillary 2.29 ; length of caudal peduncle 1.31; depth of the same 3.16; base of dorsal fin 1.27 ; same of the anal fin 1.49 ; longest dorsal ray 2.81; longest anal ray 2.61; pectoral 3.00 ; ventral 2.76. Longest gill-raker on first arch 1.49 in diameter of eye. Body elongate and compressed ; upper profile of head roundly convex at the interorbital region. Snout a little longer than half the diameter of eye ; lower jaw slightly projecting beyond the upper when mouth is closed. Mouth large, maxillary extending below posterior edge of orbit ; teeth on the premaxillary and the lower jaw small and slender, arranged in a single series, the tips curved inward and their elongated basal parts coalescent with each other (Fig. 2); maxillary with 2 or 3small, slender teeth at the middle part of the bone ; vomer and palatines edentulous. Eye about as long as half the length of postorbital part of head. Gills 4; gill-rakers slender and strongly compressed, each sparsely armed with very slender spines on both anterior and posterior surface. Pseudobranchae com-posdd of 10 short but broad gill-lamellae. Dorsal inserted at the posterior one-third of the body exclusive of caudal and ends above the base of antepenult anal ray ; anal begins below base of fifth dorsal ray. Pectoral short, extending about two-ninths the way between origin of the pectoral and that of the ventral ; ventral rather large, reaches slightly beyond the midway between origin of the ventral and that of the anal. Body covered with a thick, scaleless longitudinally wrinkled skin and scattered with granular nodules. Body jet black ; head and fins except for the whitish pectoral are grayish brown. Mouth and the wall of the branchial chamber are blackish. In the present specimen the depth of the body much deeper, eye larger and the interorbital space broader than those of the holotype. The maxillary extending below posterior margin of orbit instead of the below posterior margin of the pupil, and the base of dorsal ends vertical above the base of the antepenult anal ray, never extending above base of last anal ray as in the holotype. It should be herein mentioned that the gill-rakers on first arch 8+19 in our specimen instead of being 8+10 in holotype. The present species near R. lividus (Brauer) and R. squamilaterus (Alcock) at least in having distinct lateral line, but distinguishable from them iu having much smalle pectorals. Xenodermichthys funebris Fowler, which should be referable to the genus Rouleina, closely resembling the pressnt species in having distinct lateral line, elevated interorbital region and small pectorals, but the former having much smaller ventral and shorter lower jaw which included under the upper jaw when mouth is closed.
The present paper gives the results of my observation of the egg-capusules of the 10 species belonging to the family Rajidae, viz., Raja kenojei, R. garmani, R. macrophthaima, R. hoilandii, R. fusca, R. meerdervoortii, R. putchva, R. parmifera, R. iso-trachys and R. diplotaenia, which have been collected in Japan and adjoining waters. Based upon the external as well as the histological features it was found that the capsules are divided into four types, which are called herein types Kenojei, Soldatovi, Parmifera and Isotrachys respectively. Type-Kenojei: This type involves Raja kenojei, R. garmani, R. macrophthalma, R. holiandii, R. fusca and R. meerdervoortii meerdervoortii. The egg-capsule is of smooth surface and with short projections (horns) at the four corners (Fig. 1, KE, GA, MA, HO, FIT, ME). Of 6 species aforementioned the last two ones are closely related, characterized by having the horizontal thin horny layers, and the upper most layer bearing minute tubercles on the surface (Fig. 2, FIT, ME). In the other 4 species, however, a pulpy layer are found to exist between outer and inner layers (Fig. 2. KE, GA, HO, MA). Type-Pulchra: This type involes Raja pulchra only. The external form of the capsule is chara3terized by having a broad notch along the both lateral sides and a very short flattened horn at each corner (Fig. 1. SO). The outer layer of the capsule is composed of several zones of fibrous tissue running lengthwise series. The fibers become larger toward the surface, the ones on outermost layer usually tubular and easily spill by themselves without giving any strong friction. The surface of the capsule, therefore, is rather rough (Fig. 2. SO). Type-Parmifera: This type is represented by Raja parmifera. The capsule closely related to that of Type-Kenojei, but the horns rather long and flattend (Fig. 1. PA), the outermost horny layer is represented by stout linear ridges run-fling lengthwise series (Fig. 2. PA). Type-Isotrachys: This type is exemplified by Raja isotrachys and R. dipiotaenia. The horns are very long and filamentous, the anterior ones much longer than those of the posterior ones (Fig. 1. IS, DI). The outer horny layer is peculiar, armed with numerous series of minute velvety pricks (Fig. 2. IS, DI).
The growth of the tumours recorded of Japanese fresh water fishes up to the present are nine cases in all, namely two cases of Epithelioma. in Carassi us auratus, one case of Fibroepithelioma, two case of Papilloma, one case of Fibroma, and one case of Fibromyxoma, these all in gold fishes, and one case of Lipoma in Plecoglossus altivelis. One fish (Hypomesus olidus) with a large tumour in the trunk muscle was captured in Kizaki Lake in Nagano Pref., in Feb. 1936; and fortuuately the material preserbed in formaline came under my observation, and is described below. Macroscopic state: Thet urmour, which is sitmated. on the right side of the body extending from the upper part of the lateral line to the dorsal part at the front of the dorsal fin, is roughly ovoid in shape. 2.3 cm long, 1.7 cm broad, and 0.5 cmhigh. (Fig. 1.). The cross section at the middle part of the tumour is almost circuler, the colour being grayish white, not so hard as the normal muscular tissue. Metastasis not present. Microscopec state: The tumour tissue consists of a large amount of not differentiated parenehymatous cells, rather a few fibrous stroma and blood vessels. The tumour tissue and the surraunding normal tissue is marked. The tumour cells are mixed closely with fibrous stroma, their forms irregular and indistinct with some protoplasm and round nucleus, but they show a tendency totransform into a spindle from and the mass of these cells are arranged in a swirl like current, and moreover the formation of fibrous tissue is observed in some parts. (Fig. 2.). For the above characters the neoplasm may be diagnosed as fibroplastic Sarcoma. This tumour may be comparatively benign and seems to have slowly grown. The causal genesis of this tumour is unknown.
Most of the Japanese ichthyologists consider that Bembrops caudimacula is confined to the near coasts of Honsiu, Shikoku, Kiusiu and Formosa. As already pointed out by Alcock (1902). B. caudimacuta has wide but isolate distribution from the seas of Japan, the Bay of Bengal, the Gulf of Mexico and to off the Atlantic coasts of North America. The present author has examined and sketched an adult specimen (total length 245 mm.) taken near Heda, Suruga Bay, and compared it with figures of specimens of Goode & Bean (1895) and Alcock (1902). From the result of the comparison the author finds that two figures used by the above gentlemen are no doubt junenile examples with short first dorsal spine and with a fine eye-like dark spot on the upper side near the base of the caudal fin. The adult specimen from Suruga Bay, however, has a rather elongate and curved first dorsal spine, and has no eye-like spot on the upper side near the base of the caudal, while it has a dark longitudinal band on the lower margin of the caudal. Moreover, the author points out the individual variation concerning the number, of dorsal spines and number of scales on lateral line. The two scientific names: Hypeicometes gobioides Goode (1880) and Bathypercis platyrhynchus Alcock have thus become pure synonyms of Bembrops caudimacula of Steindachner (1876).