47° BOTANICAL GAZETTE [ JUNE 



simpler explanation may be given by assuming that the male is homozygous and 

 the female heterozygous with respect to sex, and that there is a repulsion between 

 the determinant for the grossulariata character and that for the female sex. These 

 assumptions fit all of the facts brought to light in the crosses of Abraxas. This 

 point of view has been briefly restated by Doncaster? in a report to the Evolu- 

 tion Committee of the Royal Society, where a summary of the matings and their 

 results is given. Another case has been reported which seems to correspond very 

 closely with that of Abraxas. The "cinnamon" canaries, i.e., those having 

 plumage of a brownish tint, have pink eyes when hatched. The green canary 

 has Mack eyes. Misses Durham and Marrayat 8 have found that when a 

 pink-eyed hen-canary is crossed with a black -eyed cock, all the young of both 

 sexes are black-eyed. The reciprocal cross shows all the male offspring black- 

 eyed, while all the pink-eyed offspring are females, though a few black-eyed hens 

 may occur. The latter are as yet unexplained, but there seems to be little doubt 

 that this cinnamon canary will find an explanation essentially like that given for 

 Abraxas. 



Great advances have likewise been made in the study of the determination 

 of sex from the ecological side, mainly through the work of McClung, Stevens, 

 Morgan, \\ ilson, and their students. In nearly one-hundred species of insects 

 belonging chiefly to the Hemiptera and Coleoptera, it has been found that there 

 are definite chromosomal differences between the male and female, and that the 

 odd chromosomes, or "accessory" chromosomes as they were called by McClung, 

 are so distributed at the time of the reduction division that all the female germ- 

 cells are alike, while the male germ-cells are of two kinds. The chromosome group 

 of one of these two types of male germ-cells is like that of the egg-cell, and when 

 such a sperm fertilizes an egg, a female zygote is produced. The other type of 

 sperm has a chromosome group unlike that of the egg, and fertilization with such 

 a sperm produces a male zygote. 



An excellent resume of this work and a discussion of the entire problem of sex- 

 heredity >s given by Wilson, » who has been most prominently engaged in these new 



tology 



other, Wilson- lays emphasis upon the necessity of bringing different methods of 

 scientific investigation to bear upon difficult scientific problems like this, and the 



depe 

 cialization this is more fundamental 'tharfever before. ^S^milarTooperation wJuTd 

 even improve general discussions of a subject which is being developed simultane- 

 ously by diffe rent methods, for it has become difficult for anyone to give an ade- 



i Doxcaster, L., On sex-inheritance in the moth, Abraxas grossulariata and its 

 van lacticolor. Reports to the Evolution Committee 4:53-57. 1908. 



8 Durham, F. M., and Marryat, D. C. E, Note on the inheritance of sex in 

 Canaries. Reports to the Evolution Committee 4:57-60. r 9 o8. 



9 V\ ilson, E, B., Recent researches on the determination and heredity of sex. 

 Science N. S. 29 : 53 - 70 . 1909. 



