Mabch 5, 1909] 



SCIENCE 



393 



and a typical odd chromosome is present. In 

 Syromastes the spermatogonia! number is 22, 

 the " accessory " being represented by two 

 chromosomes, and the number 24 is inferred 

 for the female. A general review is given of 

 the facts thus far determined in this field. 

 N. M. Stevens contributes " Further Studies 

 on the Chromosomes of the Coleoptera " and 

 " An Unpaired Heterochromosome in the 

 Aphids." David Day Whitney writes on 

 " The Effect of a Centrifugal Force upon the 

 Development and Sex of Parthenogenetic Eggs 

 of Eydatina senta." The unsegmented eggs 

 were centrifuged so that their contents were 

 separated into three layers. These layers were 

 variously arranged in their relation to the first 

 cleavage plane and consequently a different 

 distribution of the egg material occurred in 

 each of the cells at the first cleavage. From 

 such eggs normal individuals developed, grew 

 to maturity, and produced normal offspring. 

 No change in the sex ratio occurred. The 

 same author has an article on " Observations 

 on the Maturation Stages of the Partheno- 

 genetic and Sexual Eggs of Mydatina senta." 

 In the female parthenogenetic egg there is no 

 reduction in the number of chromosomes dur- 

 ing maturation but in the male parthenogen- 

 etic egg and also in the fertilized egg there is 

 a reduction in the number of chromosomes. 

 One polar body is formed by the female par- 

 thenogenetic egg and two polar bodies are 

 formed by the male parthenogenetic egg. 



A NEW VARIETY OF ASYMMETRY EX- 

 HIBITED BY THE NITROGEN ATOM 

 A NUMBER of organic compounds are known 

 the isomerism of which is due to the different 

 spatial arrangement of certain groups around 

 a nitrogen atom. The most familiar examples 

 are the oxines, such as benzaldoxine, which 

 exists in the forms. 



CsHjCH and 

 NOH 



CaH^CH, 



HON 



gen atom is linked to five dissimilar groups, 

 as, for example, in the compound. 



cHs. CI .c,: 



X 



CsHb' 



CHaCaHR 



which exists in three forms. One is optically 

 inactive (racemic) and the other two rotate 

 the plane of polarized light to the right and 

 left, respectively. 



Similar varieties of isomerism are, of course, 

 common in the case of analogous carbon com- 

 pounds free from nitrogen. 



Hitherto it has been believed that the dif- 

 ference in optical behavior mentioned above 

 could not be exhibited unless all five of the 

 groups linked to the nitrogen were unlike, but 

 J. Meisenheimer' has just shown that this is 

 not the case. 



When methylethylaniline. 



termed the syn- and anti- modifications, re- 

 spectively. 



A second variety of isomerism is recognized 

 which is dependent on the fact that the nitro- 



3eH5N<C 



CH, 



CnH. 



is treated with hydrogen peroxide, in presence 

 of sulphuric acid, methylethylaniline oxide. 



CH. 



CeHs' 



> 



.-CA 



^0 



is formed. It is a crystalline, basic substance 

 and is optically inactive. By the fractional 

 crystallization of its (^-bromcamphorsulphonic 

 salt it is separated into two modifications. 

 From these the corresponding free bases may 

 be isolated and other salts prepared. These 

 free bases are relatively stable and they rotate 

 the polarized light to the right and left, re- 

 spectively, the rotation being equal in degree. 

 It is, at present, uncertain whether these 

 optically active free bases have the anhydro 

 formula given above, with the double linkage 

 between nitrogen and oxygen, or whether they 

 are dihydroxides. 



CHi 

 C,H, 



X 



yOA 

 e-OH . 

 \0H 



In either case, however, the isomerism is of 

 an entirely new type. It will be interesting 

 to see whether it is possible to prepare analo- 

 'Ber. deut. Chem. Ges., 41, 3966, 1908. 



