Manchester Memoirs, Vol. I. (1906), No. 6. 13 



which had been cut as they are often long and curved. 

 After the reabsorption of the polar body, the polar nucleus 

 appears to take no further part in the subsequent cleavage 

 stages. A simple mass of chromatic substance can be 

 followed to a late segmentation stage. 



Stschelkanovzew believes that there is a passage of 

 achromatic material from the cytoplasm of the ovum into 

 the egg-nucleus, where it is changed into chromatic 

 substance. It is interesting to note that the oocytes which 

 develop into parthenogenetic ova are different in character 

 and more numerous in the ovary than the fertile ova. 

 They are smaller and very poor in yolk, the difference 

 between the two kinds of ovary being very noticeable, 

 even before any maturation has taken place. This fact is 

 of some importance as showing that the egg is already 

 destined in the ovary oi ApJiis to be either parthenogenetic 

 or fertile. This may be either a state of affairs which has 

 been arrived at through very many generations of 

 parthenogenetic cycles, the phenomenon having been long 

 acquired, or it may be the effect of nutrition upon the 

 reproduction of sex. 



ORTHOPTERA. 

 Parthenogenesis occasionally occurs in this group, and 

 although it has been studied in a general manner, I am 

 unacquainted with any cytological investigations. 



COLEOPTERA. 



Osborne first recorded the occurrence of partheno- 

 genesis in this order. The only investigation which has 

 been made into the cytological changes is that of Saling 

 (82) on Tenebrio inolitor. The ovum after some remarkable 

 nuclear changes, which I am inclined to believe were of a 

 pathological nature, failed to segment. Very brief reference 

 is made to the maturation stages. 



