X 



CYTOLOGY 



4. Which of the two Divisiofis of the Meiotic Phase effects 



the Separation of the Hojnologous Chromosovies ? . 54 



5. Synizesis . . ■ ■ ■ .54 

 C. Meiosis in the Female . . . • • 55 



I . The Continuity of the Chromosomes . . -59 



The Relation between the Chromosomes and the Nucleoli 62 

 The Connection between the Genrmtal Vesicle atid Yolk 



Formation . . . ■ ■ -63 



Does any Stage comparable to the Germinal Vesicle occur 

 in Spermatogenesis ? . . . . .65 



2. 

 3- 



4- 



CHAPTER III 



Syngamy, Early Development, Parthenogenesis . 



A. The Development ok the Spermatozoon 



B. Syngamy ..... 



C. Gonomery ..... 



D. The Germ-Tr.4ck .... 



E. Parthenogenesis .... 



1. Obligatory Parthenogenesis 



2. Facultative Parthetiogencsis 



3. The Homology of the Meiotic Divisions in Obligatory 



arid Facultative Parthenogenesis 



4. Artificial Parthenogenesis 



67 

 67 

 71 



n 

 79 



86 

 87 

 91 



94 

 94 



CHAPTER IV 



'^ The Sex Chromosomes . . . . . -98 



1. The Sex Chromosomes in Insects . . .98 



2. Which of the two Meiotic Divisions acts as the Reduction 



Division for the Sex Chromosomes ? . . .102 



3. Various Forins of the X a7id Y Chromosomes . .104 



4. Behaviour of the Sex Chromosomes during Syndesis and 



the Meiotic Prophase^ and outside the Meiotic Phase . 1 06 



5. Sex Chromosomes in Animals other than Insects . 109 



6. Cases where the Differential Sex Chromosome is present 



in the Female . . . .111 



7. Some Special Life Histories . . . .113 



8. The Relation bctioeen the Sex Chrotnosomes and the 



Determination of Sex . . . .121 



