HO H. H. NEWMAN. 



IX 7 About 8 per cent, of maturated eggs with narrow 



membranes ; about 3 per cent, of eggs without 

 membranes showing first steps in cleavage, a few 

 having completed the first cleavage. 



Sy 2 A few eggs in 4- and 8-cell stages. 



3o l / 2 A fraction of i per cent, of larvae undergoing gas- 



trulation, and swimming about, the best of them 

 being nearly normal in appearance. 

 78 All larvae dead. 



X 7*4 About 5 per cent, of eggs with fully typical mem- 

 branes, no cleavage stages. 



1/2 Over 50 per cent, of maturated eggs in cleavage 



stages, without membranes, ranging from 2 to 8 

 cells. No eggs with membranes segmenting. 



31 About 75 per cent, of all maturated eggs have un- 

 dergone cleavage without membrane formation, 

 and are in various stages ranging from early 

 cleavage to gastrulse. Numerous dwarf blastulae, 

 due to blastolomy ; many gastrulse with plural 

 archentera ; solid blastulae and exogastrulas in 

 considerable numbers. All were swimming about 

 on the bottom of the bowl. This culture was 

 made the basis of a study of the more advanced 

 development of parthenogenetic eggs and will be 

 referred to in more detail in a subsequent dis- 

 cussion. 



SIGNIFICANT POINTS BROUGHT OUT BY THE DATA SHOWN IN 



THE ABOVE SCHEDULE. 



1. Membrane formation occurs in exactly half of the experi- 

 ments here described. It was observed in from i to 8 per cent, 

 of the maturated eggs. 



2. The degree of completeness of membrane formation varies 

 greatly in different sets of eggs and in different eggs of a given 

 set. In some eggs the membrane is so little lifted from the sur- 

 face of the egg as to be scarcely noticeable, ibut in others the 

 membrane is indistinguishable from that seen in fertilized eggs. 



3. Eggs that form membranes, whether narrow or wide, do not 

 further develop, but undergo cytolysis within twenty-four hours. 



4. The percentage of maturated eggs that undergo partheno- 

 genetic development varies from none to about seventy-five; in 

 experiment II no cleavage occurred, while in experiment X 75 

 per cent, of all maturated eggs at least began cleavage. The aver- 



