502 LIFE : OUTLINES OF GENERAL BIOLOGY 



we have given the answer that the characters are all correlated, they 

 are there or not there en bloc, they form a sex-Unked assemblance. 

 And as a reason for this correlation we have suggested (i) that all 

 mascuUne (or feminine) characters originally arose as germinal 

 variations in gametes predisposed to develop into males (or females), 

 and (2) that in some cases these variations may be plausibly inter- 

 preted as congruent or sohdary with the characteristic male (or 

 female) diathesis. And to this there requires to be added the very 

 imjx)rtant consideration that just as a thjToid gland and a pituitary 

 gland have arisen in the course of evolution with fundamentally 

 important functions in the internal economy of the organism, so 

 in the course of evolution the gonadial glands have arisen, whose 

 internal secretions, working in harmony with other internal secre- 

 tions, serve as the liberating stimuli and indirectly as the regulators 

 of the development of the sex-characters. 



An Illustration: Winged and Wingless Greenflies. — 

 Some greenflies or Aphids give origin parthenogenetically to 

 winged and wingless progeny in varying proportions. It can 

 hardly be doubted that the capacity for having wings is part of the 

 normal inheritance, and that the winglessness is what may be called 

 a minus variation, like the absence of horns in a horned race of 

 cattle, or the absence of a tail in a kitten, or the absence of hair on 

 a child. Some Mendelians would say that the winglessness is due to 

 the loss of a particular hereditary factor or gene (or group of genes). 

 In the lineage or in the maturation of some of the ova the hereditary 

 representative of wings may be lost. This is the kind of interpreta- 

 tion that is usually given of such a condition as albinism, where 

 there has been a loss of the factor or factors for pigmentation. 



But Mr. Lloyd Ackerman, who has been studying the grain Aphid 

 {Rhopalosiphon prunifolicB) , indicates another kind of interpreta- 

 tion. Perhaps what inhibits the development of wings is a variation 

 in the general physiology of the organism. In the hrcmolymph, 

 which corresponds to blood in insects, there are two kinds of fat or 

 lipoid globules, and two kinds of pigmented globules — green and 

 brown. The brown globules are delicate unstable structures which 

 are readily disrupted, and the wing production appears to be 

 dependent on their breaking down. The instability of the Aphid as 

 regards wings appears to be due to the instability of the brown 

 globules. Other features accompany the winglessness, such as 

 peculiarities in size, colour, markings, sensitiveness, as well as the 

 solidification of the fat globules. But the general idea is important 

 that a biocliemical cltangc tnay greatly influence tlte developntental 

 expression of the inheritance. 



THE MANOILOV TEST FOR SEX.— Some interesting chemical 

 tests for sex have been proposed by Manoilov and by others. The 



