ON THE DEVELOPMENT OF PARASITIC COPEPODS. 69 



V. POLYSPERMY. 



In Lcemargus inuricatus I have found many eggs into which a 

 number of spermatozoa had entered. In one case the whole egg 

 string was of such eggs ; in the other cases only a few such eggs 

 were found in a string. The " development " of these eggs falls 

 under three classes : 



1. The 9 pronucleus and the c? pronuclei fuse to form one 

 nucleus in the center of the egg which does not develop further. 



2. In the center of the egg a multipolar spindle is formed 

 usually of three principal poles and one minor pole. The result- 

 ing division in all observed cases cleaves the egg into three sub- 

 equal cells, in each of which a bipolar spindle with a very large 

 number of chromosomes is formed. Further development is 

 very irregular. 



3. A bipolar spindle with an immense number of chromosomes 

 is formed in the center of the egg. Apart from the number of 

 chromosomes the cleavage approaches the normal type, especi- 

 ally up to the 4 cell stage after which it diverges more and 

 more from the normal type. I am led to believe by certain eggs 

 that show an intermediate stage between a multipolar and a 

 bipolar spindle, that the bipolar spindles in the first cleavage of 

 these eggs are formed out of multipolar spindles. 



As all of these eggs were already mounted (by Professor Rynear- 

 son) I was not able to observe whether the axes of these poly- 

 spermous eggs that approached the normal type in development 

 were the same as in normal eggs. I have not observed whether 

 maturation takes place in polyspermous eggs the cleavage 

 spindles are very different from normal cleavage spindles, and 

 are very similar to normal maturation spindles. This may be due 

 to a tendency to throw out the excess of chromatin, and in some 

 cases I have found a mass of very small cells extruded from the 

 egg, not always, however, in the position in which polar bodies 

 normally form. There are often many asters in the egg uncon- 

 nected with chromosomes, and this may account for rounded 

 masses of yolk that are sometimes cut off from the egg. 



