6 THOS. II. MoM'.OMKKY, JK. 



<>t" papers, and ha\e expre-- cd my-elf only once on tin- matter, 

 in H)o6, in considering \Yil-on'-, conu-ntion which 1 iv-anled 

 "a very plausible conclusion, but thriv are in particular two 

 phenomena which must be explained before it can be accepted. 

 One is, how an allo-ome becomes lost in the spermatogenesis; 

 and the other is, how the allosomes introduced by the spermato- 

 zoon inio the ovum behave during the ovogenetic cycle; on both 

 of the-e questions we know as yet practically nothing." 



Gross (1904) objected to the hypothesis of McClung, (i) that 

 it i- not proven that accessory chromosomes arc ab-ent in female-, 

 and ( 2 ) the case of the bee, where males develop from unfertili/ed 

 fS. He also believed that the spcrmato/oa with mono-oiiies 

 may be incapable of fertilization; but 1'ailrd to note that such 

 supposition could not be applied to -perm with idiochromo-onie-. 



Foot and Strobell (1909) urged that the theory of the indi\ id- 

 uality of the chromosomes is not proven today, a decided minor- 

 it} view. They also held that the allosomes of Eiischistits are 

 not chromo-onies at all, and an- variable in number, which is in 

 direct opposition to the discoveries of Wilson and myself. "In 

 the case of J-'.nscliislits we are told that the larger of the two 

 chromatin nucleoli of the spermatocyte is the homologiu- of the 

 accessor) chromosome of other forms, and if this interpretation 

 i- correcl \\e may expect to find a large bixaleni or two unixalent 

 chromatin nucleoli in the growing oocytes." Hut they find no 

 such bodie- in oocytes, and therefore conclude that the chroiiialin 

 nucleoli of the male AVC never transmitted to the egg, an- not 

 chromosomes at all, and hence cannot lie ^ex-determining", this 

 objection lo the Wilson-Stevens theory i- inadmissible 



An explanation suggests itself to me \\liy allo-onies, \\hich all 

 lence lead-- us to belie\c mu^t be transmitted to eggs by 

 fertilization, acl in a dilfereni \\a\ in the oogenetic cycle. That 

 is, in spermaii);jeiie-i- ilie -ingle mono-ome, or the pair of un- 

 C(|ual idiochromosonu-^. bi-ha\e dillereiith troni the oihi'r chro- 

 mosomes, remaining den-e and compact in the grout h |eriod 

 of the SpermatOCytCS, probablx because lhe\ are there unpaired 

 (monosome) or of unequal size idiochromo-ome!. \\hili' all the 

 other chromosome- are paired, and the tun of each pair seemingly 

 alike. In the growth period of the OOC} tes, on the contrar\-. ilie 



