TO THE EMBRYOLOGY OF AMPHIBIA. 



and the frothy envelope is strongly viscous. The eggs, however, 

 become gradually firmer in texture and are ready to begin seg- 

 mentation in 4-5 hours after deposition. 



During the breeding season of 1899, I kept a pair of the 

 animals in a glass-flask on my table, in the manner already 

 described in my former paper, and obtained a number of eggs 

 from them. Another pair kept in a glass-cup and carried about 

 for three days in my pocket deposited only a limited number of 

 eggs. These eggs as well as those produced by the first-mentioned 

 pair showed more or less abnormality in their development — due, 

 it seems to me, to the forced arresting of oviposition and to the 

 unnatural treatment to which the eggs had been subjected. Even 

 the eggs deposited in a natural position are apt to show some 

 abnormalities if they are subjected to unfavorable treatment. This 

 tendency to abnormalities is not, however, peculiar to the eggs of 

 this animal. So far as my experiences go, those of other Amphi- 

 bians living in Japan (such as Rana japonica or Bufo japonica) 

 show themselves similarly sensitive even to slightly altered condi- 

 tions in their environment. I am now inclined to think that 

 the process of segmentation in Rhacophorus eggs as described in 

 my former paper is in some respects abnormal, as the eggs then 

 observed were deposited by a pair of animals in captivity. 



The first and second cleavage-lines make the figure of a 

 cross, as is usual in amphibian eggs (Figs. 1-3). The third 

 cleavage plane appears, in most eggs, symmetrically upon the 

 second cleavage-line at nearly equal distances from the crossing 

 point of the first two cleavage-lines (Fig. 4). Thus, the third 

 cleavage must be considered as in a vertical, rather than in the 

 horizontal plane, (to which I have previously referred it), and shows 

 itself in four separate line* starting from the second cleavage-line 



