ARTIFICIAL PARTHENOGENESIS IN CUMINGIA 15 



In most experiments, no attempt was made to count the per- 

 centage of maturation, as the polar bodies would be hidden be- 

 hind the egg in many cases. In the experiment just described, 

 the cojnts were made to give the relative numbers in the two 

 parts of the experiment. In one half 22 per cent of the eggs had 

 polar bodies that were in such a position that they could be 

 seen without rolling the eggs around; in the other half the count 

 was only 10 per cent. The percentage of cleavage, on the other 

 hand, represents the actual proportion of the eggs that are 

 undergoing segmentation, as a 2-cell stage is recognizable as 

 such from any point of view. 



These experiments serve as an illustration to show that, in 

 general, in a case where polar body formation is good, cleavage 

 is poor and few larvae develop. But they do not prove conclu- 

 sively that larvae come from eggs in which maturation has been 

 suppressed. To do this, it was necessary to resort to the 

 method of isolating eggs without polar bodies and observing 

 their development. The highest powers of the binocular micro- 

 scope were used in selecting the eggs, and each one picked out 

 was first rolled around with a fine brush and viewed from all 

 sides to make sure that it had, in fact, no polar bodies. In all, 

 1215 such eggs were isolated; and fr.om these, five larvae devel- 

 oped. One of these larvae is shown in text-figure 2, 2. It is 

 smaller than the larva from the normally fertilized egg, but is 

 evidently cellular, and is fairly normal in external appearance. 



This showed, then, that larvae could develop from eggs 

 which had not formed polar bodies, but did not prove that eggs 

 which had undergone maturation could not also form larvae. 

 That such eggs could divide at least once was shown from the 

 2-cell stages with polar bodies which were occasionally found in 

 the cultures. 313 eggs with one or two polar bodies were iso- 

 lated, and from these a single swimmer developed. This was 

 not, however, a normal larva. It is illustrated in text-figure 2, 

 3. Evidently it has developed without further cleavage from a 

 2-cell stage. 



Abnormal swimmers like this are not uncommon in the ex- 

 periments. Sometimes an egg will be found that has been 



