430 ANN BISHOP 



very swollen micronuclei possibly were about to degenerate 

 and not to divide. No stages demonstrating the formation and 

 crossing over of the gamete nuclei nor the degeneration of 

 the surplus ones have been obtained. 



In a preparation of an exconjugant, made soon after its 

 separation, a spindle was seen at the anterior end of the body. 

 This spindle (see PI. 23, fig. 14) was more elongated than those 

 present in the conjugants. It was immediately surrounded by 

 denser protoplasm than that of which the rest of the body 

 was composed. It also was at the equatorial plate stage. A 

 very careful investigation of the rest of the animal did not 

 reveal the presence of other spindles nor of other micronuclei. 

 This spindle was therefore regarded as that of the zygote 

 nucleus, and it was concluded that the other micronuclei had 

 all degenerated. Subsequent stages in division of the nuclei 

 in the exconjugant were not seen. 



No further stages of the division of the micronuclei were 

 discovered in the exconjugants. In two exconjugants four, 

 and in one preparation eight, micronuclei were discovered in 

 the neighbourhood of the two rudiments of the meganucleus. 

 In no preparations were micronuclei found attached to the edge 

 of the meganuclear discs as Mulsow found in exconjugants of 

 Stentor. 



I should like to take this opportunity to thank the many 

 friends who have so kindly given me helpful advice and sugges- 

 tions. Particularly I should like to thank Professor Hickson 

 for the stimulating interest he has taken in the work. My 

 sincerest thanks are offered also to Dr. G. Lapage for the 

 help and encouragement he has given me throughout ; to 

 Mr. Wadsworth for his advice particularly on many matters of 

 technique ; and to Dr. Clifford Dobell for the assistance he 

 so kindly gave to a stranger. Without their help the omissions 

 and mistakes in this paper would have been considerably 

 greater. 



