4 ART. 3. S. IKEDA : CONTRIBUTIONS 



Before going further, I wish to express my heartfelt thanks 

 to Prof. K. Mitsukuri for much invaluable advice and for his 

 kindness in working over the manuscripts of the present article. 



I. 



GENERAL ACCOUNT OF EXTERNAL DEVELOPMENTAL 

 CHANGES IN RHACOPHORUS EGGS. 



During several years past, I have frequently gone over the 

 external changes which take place in the eggs of Rhacophorus. 

 Some features which are peculiar to this species are certainly 

 remarkable, and seem to me to deserve special notice from the 

 point of view of comparative embryology. Some of these, as 

 well as the general habits and the mode of the egg-deposition of 

 this animal, I have already described briefly in my former paper 

 {Joe. cit.). I may, however, add a few more facts here. 



As already stated, the eggs of this animal are absolutely 

 without pigment and are placed in a frothy mass, concealed in 

 subterranean cavities in the muddy banks of paddy-fields, ponds, 

 and other shallow bodies of water. Deposition takes place mostly 

 at night, during the breeding season which extends from April 

 to May. It is an interesting fact that in the earlier part of the 

 season, the animal deposits its eggs mostly on slopes which face 

 east, south, or south-east, while toward the end of the season, 

 when the atmospheric temperature has become mild, any spot 

 favorable for deposition, even if it faces north or north-east, is 

 indifferently chosen. 



The eggs just deposited are extremely delicate and flabby, 



