EFFECTS OF AGING UPON GERM CELLS AND 

 UPON EARLY DEVELOPMENT. 



PART II., CHANGES IN MODERATELY AGED EGGS AND SPERM. 



A. J. GOLDFARB, 

 COLLEGE OF THE CITY OF NEW YORK. 



CONTENTS. 



PAGE. 



Change in Size of Eggs 373 



Change in Jelly Layer 377 



Change in Membrane Formation 380 



Change in Cleavage 386 



(a) Synchronous Aging of Eggs and Sperm 386 



(b) Fresh Sperm by Aging Eggs 389 



(c) Aging Sperm by Fresh Eggs 395 



(<f) Longevity of Sperm and Eggs 395 



(e) Rate of Cleavage 399 



Correlation of Changes 403 



Summary 408 



In a previous publication (Goldfarb, '17), the writer deter- 

 mined the variation of freshly liberated sperm and eggs from 

 freshly collected sea urchins of three different species. Two of 

 these, Toxopneustes and Hipponoe, inhabit the shallow tropical 

 waters of the Dry Tortugas, and the third, Arbacia, is common 

 in the deeper colder waters near Woods Hole, Mass. In each 

 species preliminary experiments had been made to ascertain the 

 optimum conditions of development, such as volume and surface 

 and filtration of sea water, concentration of eggs and sperm, etc., 

 and such optimum conditions were used in all subsequent ex- 

 perimentation. 



It was shown that even under these constant and optimum 

 conditions, the freshly liberated eggs of different females varied 

 in respect to (i) size, (2) jelly layer, (3) membrane formation, 

 and (4) cleavage; that there was a surprisingly large variation, 

 with respect to each of these four classes, in the eggs of different 

 females; that the sperm of different males also varied, but to a 

 much less degree. And finally the range of variation was deter- 

 mined for each species. 



372 



