-I IM.KM Ml KARY CHROMOSOMES IN CHUTHOPHILUS. 22 



-- i 



In Ceuthophilus the first maturation mitosis is therefore a 

 segregating division of the previously paired and united homolo- 

 gous univalent chromosomes, while the second mitosis is as clearly 

 an equational division of all of the univalent chromosomes 

 in< hiding A". 



DISCUSSION. 



In an earli< T -tudy ('05) of the spermatogenesis of t\v<> other 

 species of ( >nln>pirra, Blattella (Blatta] ennanicti and Stcnopcl- 

 nnitns (-p. I >und what seemed to be good evidence. <>t" telo- 

 synapsia '05, PI. II., Figs. 55, 56, 58, 59, 62, 63, 64, and PI. III., 

 to 115). That material I have reviewed and compared 

 with th< ' ''kilns preparations, and I find no such evidence 



it" parasynapsis in fit her of them. Naturally I expected to find 

 tel"-v n.tp-i-, in Ceuthophilus, and was surprised on working back- 

 ward t'n .in the maturation mitoses to find no evidence of telo- 

 synapsis outside of the late prophases, and abundant evidence of 

 parasynapsis in the young spermatocytes at a st.'.-^c \\lure s\n- 

 i/e-i- i- frequently found in other material. 



A ivc.-nt review of the literature on conjugation of chromo- 

 somes ha> only strengthened my previous conviction, based on 

 in\ o\\ n i \prricnce with the spermatogenesis of a variety of 

 forms that tin- phenomenon is one which vari- aly in 



ditii n-nt L;roiii of organisms, and even in dinVn-nt species of 

 the ^anic - nus, or different sexes of the same '//a, 



Stevens '03, '05; Btifo, King '07, '08). Indeed I should not be 

 Mirpri>-l it the range of variation should prove to i-\t.-nd troni 

 . ases \\lu-re there is nothing that could be called conjugation, 

 but nu-n-ly such a pairing, without contact even, as will secure 

 ition of homologous maternal and patrmul chromosomes 

 to different daughter cells, through (b) an intermediate condition 

 of telosynapsis and less intimate parasynapsis, to (c) cases where 

 hi Min )1< >;^ ii c hromosomes are so completely fused in parasynapsis 

 that it is impossible to tell whether the resulting chromosomes 

 \\ hich are segregated in mitosis are identical with those that went 

 into synap>is or not; and the variation may extend to cases 

 which may give further support to Janssens' chiasma theory 

 ('09) or to Morgan's modification of it t'i O in which homologous 

 chromosomes are supposed to be twisted tightly together in 



