CHROMOSOMES OF MOSQUITO 549 



which collect into threads at a comparatively late stage. A 

 comparable condition occurs between successive diploid mitoses. 

 I have not been able to count the number of chromosomes in 

 all stages between telophases and early prophases, but I have 

 nothing at all suggesting such a 'Brockenstadium' as Lomen 

 figures. Fine chromatic threads are visible in all 'resting' stages 

 in my material. They occur in the earliest first spermatocyte 

 nuclei (figs. 29, 30, and 31), as well as in all stages from first 

 spermatocyte telophase to second spermatocyte prophase (figs. 

 69 to 80). I therefore conclude that the chromosomes are con- 

 tinuous between mitoses and that Lomen's 'Brockenstadium' 

 and 'Verstaubungsprozess' are artifacts. 



E. CHROMOSOME NUMBER 



Stevens ('09) concludes that, in diploid mitoses of Culex 

 pipiens, each of the six chromosomes divides longitudinally, and 

 six go to each pole. Three is the reduced number appearing in 

 both maturation division. 



Taylor ('14) considers three as the somatic number. She 

 suggests that there may be but one maturation division, which 

 is equational. This, she recognizes, would involve the non- 

 participation of one of the gametic nuclei in fertilization. She 

 suggests, as an alternative, that the homologues have fused in 

 her material, thus reducing the number. She accounts for her 

 disagreement with Stevens by supposing that the latter worked 

 on Culex pungens. Stevens has used the names pungens ('09) 

 and pipiens ('11) interchangeably. They appear to be the same, 

 both taxonomically and cytolog'ically. Taylor considers that 

 one member of each pair appearing in diploid metaphase goes 

 to each pole. The homologues are thus interpreted by her as 

 daughter chromosomes. 



Lomen ('14) has three chromosomes going to each pole in all 

 anaphases, and three chromosomes appearing in prophase. But 

 his spermatogonial anaphase shown in his figure 10 could as 

 well be interpreted as having six. The prophase ' chromosomes 

 each split transversely to form the six metaphase chromosomes. 



