12 J. T. PATTERSON 



sequent history of the polar bodies, Martin in the main is in agree- 

 ment with Silvestri. His account of the organization of the 

 paranucleus and trophamnios is especially clear. 



I have given the subject of the formation of the polar nucleus, 

 which is the homologue of the paranucleus, very careful study, 

 and the conclusion at which I have arrived is based on an examina- 

 tion of several hundred eggs, both in sections and in whole mounts. 

 This conclusion is slightly at variance with that reached by Sil- 

 vestri in his studies on the egg of Litomastix. So far as the 

 formation of the polar bodies is concerned, I am in complete 

 agreement with Silvestri; but according to my observations on 

 Paracopidosomopsis, the second polar body and the inner 

 nucleus of the first body fuse to form the polar nuclerus, and this 

 occurs irrespective of the time relations between the second 

 maturation and the polar body division. 



At the close of maturation the female pronucleus moves toward 

 the sperm, which is situated at the posterior end of the egg, 

 leaving the three polar bodies at the anterior end. The polar 

 bodies are almost invariably arranged in a row (figs. 5, Ai, A 2, 

 Bi). At this stage each polar body consists of a number of 

 delicate chromatin threads or rods surrounded by a clear space. 

 In later stages the two posterior polar bodies come to lie close 

 together, in a single clear space, and somewhat apart from the 

 third or anterior group of chromatm (figs. 8, 11, 13, 14, 31). 

 In some eggs one can still recognize the individual chromosomes 

 (figs. 31, A2, Bi), but from now on their individuality gradually 

 disappears, and the single body thus formed consists of a coarse 

 reticulum of chromatin (figs. 10, 23, P). This body is of course 

 the formative polar nucleus, and by the time the four-celled 

 stage is reached it is completely organized and appears as a con- 

 spicuous figure lying at the base of the anterior process (figs. 

 17, 18, 22, P). 



In the meantime the outer nucleus of the first polar body 

 undergoes certain changes, the most iniportant of which is 

 the condensation of its chromatin into a single mass (fig. 23, 

 31, A i). This body very quickly dissolves and disappears. The 

 changes here recorded have been observed in a large number of 



