Mat 15, 1908] 



SCIENCE 



787 



on rabbits concludes tbat sex is determined 

 by the ova, which he regards as male and 

 female, respectively, or in Mendelian termin- 

 ology, that it is the female which is hetero- 

 zygous. 



There is, we think, no reason a priori why 

 in nature generally dominance should be the 

 special property of one sex alone. We rather 

 anticipate that dissimilarity will be found 

 between the great groups in this respect. 



Consistently with the view that in Verte- 

 brata the female is heterozygous, the produc- 

 tion of male secondary sexual characters 

 ensues in the female consequent on ovarian 

 disease, while castration of the male produces 

 effects which may perhaps all be regarded as 

 arrests of development. In the Crustacea, 

 however, the work of Geoffrey Smith and of 

 Potts on parasitic castration points to the 

 converse conclusion, namely, that the male is 

 there heterozygous for sex, assuming definite 

 female characters when castrated, while in 

 the female castration merely arrests develop- 

 ment. 



Correns refers to E. B. Wilson's facts re- 

 specting the accessory chromosome as support- 

 ing the view that the male is the heterozygous 

 sex, and we have lately done the same." Don- 

 caster, however, has pointed out to us what 

 must be a serious difficulty in the application 

 of this argument ; for if the male sex be dom- 

 inant, it has then to be supposed that domi- 

 nance attaches not to the presence of the ac- 

 cessory chromosome, but to its absence, since 

 it is in the female that the accessory chromo- 

 some is paired. Great weight we think must 

 be given to this criticism. Dominance, as we 

 now suppose, is due to the presence of some- 

 thing which is absent from the recessive, and 

 we are almost precluded from imagining that 

 the absence of a chromosome can be a cause 

 of the dominant quality. 



In order to bring the facts of sex inherit- 

 ance in the parthenogenetie forms (bee, aphis) 



the output of females, an opinion can scarcely be 

 formed on the cases published by Russo, for these 

 are declared to have been selected. It is to be 

 hoped that the full statistics will soon be pub- 

 lished. 

 •Science, XXVI., 1907, p. 658. 



into line with our view, it would perhaps 

 have to be supposed that sex segregation in 

 these types takes place not between gametes, 

 but between the primitive soma and the germ 

 plasm, so that the ova would all bear the 

 recessive male character and the spermatozoa 

 the dominant female factor. To discuss this 

 suggestion in detail would, however, carry us 

 beyond the scope of this note. 



R. C. PUNNETT 



W. Bateson 

 Cambeidge, England, 

 March 19, 1908 



pre-cambrian rocks in southeastern 



WYOMING ' 



During the past summer the ancient rocks 

 of the Laramie and Sherman quadrangles in 

 southeastern Wyoming were studied in some 

 detail. The maps cover a portion of the 

 Laramie Mountains and the easternmost spurs 

 of the Medicine Bow range. It appears that 

 most of the region is underlain by a coarse- 

 grained red granite, but there are scattered' 

 patches of older rocks which show various- 

 degrees of metamorphism and bear complex- 

 relations to one another. 



The oldest rocks recognized in the district 

 are a series of schists and gneisses, which are 

 largely metamorphosed volcanics, although 

 they contain some rocks clearly of sedimen- 

 tary origin, and others which are doubtful. 

 The supposed volcanics include hornblendic 

 schists and schistose rhyolites. Some occur in 

 the form of dikes, while breccias indicative 

 of surface extrusives were recognized in sev- 

 eral places. Certain highly quartzose rocks 

 and tremolite-schist are interpreted as altered 

 sediments. The rocks are so highly folded, 

 metamorphosed and cut by later intrusions- 

 that the relations of the different members to 

 each other are very obscure and have not yet 

 been elaborated. 



Next in age follows a group of granitic 

 gneisses, which are evidently metamorphosed' 

 granites. They are clearly intruded into the 

 schists just mentioned. There are at least 

 two distinct varieties of these gneisses: one- 



' Published by permission of the Director of the- 

 U. S. Geological Survey. 



