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S. tKEDA. 



mass is devoid of bubbles and shows, to a certain extent, a concentric 

 arrangement. The pigment appears first at the pectoral region of the 

 hatched larva, as in the case of fish-embryos. 



Segmentation on the whole is unequal and total, bat it shows a 

 greater approach toward the meroblastic mode than other amphibian 

 eggs ; the first horizontal cleavage plane (3rd.) is placed nearer the upper 

 pole and encircles a smaller area than in the eggs of Bufo and Rana. 

 The first and second meridional cleavage planes may reach the yolk-pole, 

 where they often cross with each other, but the subsequent meridional 

 cleavage planes do not reach the yolk-pole and end mostly at about the 

 equatorial region of the egg. Moreover at a later stage of development 

 the first two meridional cleavage planes, which once reached the 

 yolk-pole, become more and more insignificant up to the 82- or 64-cell 

 stages, when they entirely disappear, together with some other cleavage 

 planes in the lower hemisphere, while the cell outlines of the upper 

 half are still distinctly visible. 



The early development of the embryo is quite different from that 

 of other amphibians, but resembles very much that of the ganoid, which 

 is indeed the point that roused my great interest in the development 

 of the animal several years ago, when I was studying the embryology 

 of other amphibians under the direction of Prof. K. Mitsukuri. The 

 chief points of resemblance with the ganoid are as follows : (1) the 

 embryo is greatly flattened over the large yolk-mass, so that the ven- 

 trally observable organs, as the heart and the hyo-mandibular arches, 

 appear in front and at the sides of the head ; (2) the body of the embryo, 

 in later stages, is wedged into the yolk-mass, which is deeply grooved 

 along the dorso-median line. 



There are many other points which must be studied comparatively 

 with the ganoid, the teleost, and other fishes. I have, however, not yet 

 finished the microscopical study of these eggs and embryos. It is 

 my earnest hope to be able to return to this subject at a later date. 



Printed July :Ì7, 1897. 



