no CHROMOSOMES DURING SYNGAMY IN PROTOZOA 



1 







iX 



m^ 



r> 



/2 



'^ 



r of 



/J 



Fig. 65. — Nuclear Division in the Gregarine, Di])locysUs sclmeideri, to illus- 

 trate THE EeDUCTION IN THE CHROMOSOMES IN THE FiRST NuCLEAR DIVISION 



IN THE Zygote ( x 2,500). (1-3 after Dobell and Jameson, 1916; 4-14 after 

 Jameson, 1920.) 



1-3. First division in the cregarine, showinfr division and sojjaiation of the three chromosomes. 

 4-0. Third division in the gregarine, in a\ hich tlucc cliniiiKiscjnics auain divide. 

 7. Last nuclear division to form the gamete niu^lei: three chroniosumes again divide; there is 

 no reduction. 8-9. Zygote nucleus with six chromosomes. 



10. The six chromosomes arranged in three pairs. 



11, 12. Separation of the chromosomes in two groups of three (reduction). 

 13, 14. Rcconstitution of two nuclei, each with three chromosomes. 



