IO TIK'S. II. MONTI iO.MKKV, JR. 



ot the .illi >-< 'inc- are i much morecomplex than this, allowing so 

 main different chromosomal combination- in tin- -permato/oa, 

 that tin- interpretation of \vhai -permato/oa are male-producing 

 and what are female-producing becomes very difficult. Atten- 

 tion may be drawn, for example, to a case in the Hemiptcra 

 dc-cribcd by me (1901, 1906^). In -permatocytes of Calocoris 

 rapidus there are: "twelve autosomes that divide in both mitoses, 

 l\\o diplo-i.me- that do likewi-e (therefore arc probably al-o bi- 

 valent |, a -mailer monosome that does not divide in the tir-t but 

 dot- divide in the second mitosis, and a larger monosome that 

 divides in the first but not in the second mitosi-." Other com- 

 plex associations of allosomes have been de-scribed by McClung 

 and Payne. Were tin- allosomes sex-determinant-, \\c would 

 have to conclude that in certain species a considerable number of 

 the chromosomes subserve this end, which would be allotting an 

 undue amount of the nuclear material to this purpose. 



2. In all plants, with the exception of one (Salomon io) described 

 by Cardiff (1906), and in may animals, no allosomes are known, 

 yet ihe-e species have sexuality. It is probable that such struc- 

 ture- will be found in certain cases where they have m i\ been 

 o\ erlooked ; yet they are apparently absent in some cases win -re 

 -pecial >earch ha- been made for them; accordingly, at the most 

 they can IK- -ex-determinants in only a limited number ot cases. 



.v In certain species there is the phenomenon ot two sizes of 

 i-ggs, some larger that produce females, others smaller and male- 

 produeing. This is known for the Ph\ lloxerans, Rotatoria and 

 /)ino/>liilns nfxilris; another < LS6 ha- bei'ii de-cribed for an acar- 

 ine b\ Renter (19071; and I have -hown il'io;) that there are 

 two -i/es of eggs in thearaiie.nl '/'In'riili iini , though I did not 

 raise these e--- to determine their prospective sex values. These 

 two kind- of e-g- may be produced by the -ame individual, or 

 (Rotatoria, Punnet t , hjodj b\ different indi\ idnal-. These eggs 

 become distinguishable in the gn>\\ ih pei-jod, and for the 1 Mix llox- 

 erans Morgan (I'jooi has shown that the e^g i- "-e\na!l\ deter- 

 mined" before the formation < ,\ the polar bodie-. Malsen (1906) 

 held lor DitlOphiluS apdtris that the "dilTerence betueen male and 

 female eggs apparently lie- chielK in the greater or less number 

 of fusing ovogonia"; but his brief description and le\\ figures do 



