EDITH riNNEV. 



found in To.votvit'iistt's the somatic number of chromosome- i> an 

 even number in both sexes we must conclude that the odd chromo- 

 some is the eccentric member of an unequal pair. This of course 

 implies the assumption that in the odd chromosome \\ e an- dealing 

 with a univalent and not a plurivalent element. The number 

 of chromosomes in Hiplwnoi'- may or may not be even. In the 

 five species of sea-urchins already investigated the somatic num- 

 ber has been reported as even. The conclusions have however 



%* 







~ * 



.% 



: 



31a 31b * 9a 



'"'I/, 



30 



FIGS. 290 and 29^. Moira. Anapha-r from two 

 I-ii.. 30. Moira. Chromosomes from Fix- !>) -V, hook? 

 FIGS. 310 and jib. Moira. Polar views of two dauulitn plates from tin- 

 spindle. r chromosomes. !'!>;. ,}:'< is from two sections. 1,500 diameters. 



been drawn from axtTa^es of main- counts. Since the counts 

 of single plates \aried an exact statement as to whether the 

 diploid number of chromosomes is the same and even in both 

 3, Of differs, beini; e\ en in one and odd in tin- oilier, seems 

 hardly justifiable. 



In comparing daughter plates of /fif>/)oni>i' with those of 

 'I'<>.\t>f>ncnslfs I found as a rule that ihe chromosomes in '/'t>.\-<>/i- 

 >ir null's were better separated. K\ en ilu-re tlu- majorit\- of counts 

 could not be made \\ ith anv assurance of accuracy. Mi-- I let'fner 

 reported thirt\--six chi-omo-ome- for '/'.\-n/)iii'iistrs. I found four 



