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



VI. The Cytological Aspect of Parthenogenesis 

 in Insects. 



By C. Gordon Hewitt, B.Sc, 



Deiuoiistrato}- of Zoology in the Umversity of Mauchcsier. 

 Received and Read ATatrh 13th, igo6. 



The cytological aspects of the biological phenomenon 

 Parthenogenesis, that is the changes which take place in 

 the maturation and development of the unfertilized q^^%, 

 have only been studied within comparatively recent years, 

 though our knowledge of the occurrence of the pheno- 

 menon dates back to the time of Aristotle. 



At the present stage of the inquiry, it appeared to me 

 that a useful purpose would be served if a short summary 

 were made of our present knowledge of the cytological 

 phenomena associated with parthenogenesis in that group 

 of animals — the Insects, in which the problem was first 

 studied, and in which examples of the different types of 

 parthenogenesis are found. 



For the sake of brevity and clearness, little reference 

 will be made to the general parthenogenetic phenomena, 

 as these are fairly well known and have been summarised 

 recently by Phillips (78). Since his review was written, 

 our knowledge of the maturation of the parthenogenetic 

 ovum has been increased, chiefly by researches made 

 with a view to investigating the chromosomes, the study 

 of which is occupying an ever-increasing number of 

 workers. We shall have more light thrown upon those 

 great biological problems — Sex, Fertilisation, and 

 Heredity, about which, the last especially, we know 



May 2 1st, igo6. 



