484 



SCIENCE 



[N. S. Vol. XLV. No. 1168 



The comb of the capon fails to reach the 

 full development of that characteristic of the 

 Brown Leghorn cock, while in the spayed 

 female the comb becomes male-like in certain 

 individuals at least. The spurs develop on 

 the capon as well as on the cock — a result that 

 shows that this secondary sexual character at 

 least is little if at all affected by the removal 

 of the testes. In the Brown Leghorn hen and 

 more commonly in other breeds, spurs may 

 occur on the female occasionally, and even 

 be developed as completely as in the male, 

 but they developed in all the successfully 

 spayed females. In the light of the occa- 

 sional occurrence of spur in the female, the 

 results after spaying can not be definitely 

 ascribed to the absence of the ovary, although 

 this is the more probable conclusion. 



In castrated drakes and in spayed ducks 

 the voice remains normal " except that some 

 castrated females occasionally give voice to 

 a sound similar to the drake's." In fowls, on 

 the other hand, both sexes after gonadectomy 

 " are disinclined to give voice," although 

 capons may give all the sounds characteristic 

 of clarion (but rarely do so). The spayed 

 females were not observed to crow. 



At the time when Goodale's paper was 

 written the effect of castration on hen- 

 feathered males (that are characteristic of 

 certain races, notably Sebrights, Hamburgs 

 and Campines) was not known. Since then 

 the reviewer has shown that not only the Fj 

 (dominant) and F. hen-feathered males as- 

 simie the full plumage of the cock, but that 

 this holds true for the pure Sebright cock 

 also. 



Goodale discusses the nature of the influ- 

 ence that brings about the change after re- 

 moval of the ovary and concludes that the 

 ovary secretes some substance that holds in 

 check the development of full male characters 

 that may be assumed to be inherited through 

 hoth sexes. A parallel case is furnished by 

 the experiments referred to above, in crosses 

 of Sebrights and Black Breasted Game 

 Bantams, that show that hen feathering is 

 transmitted as a non-sex-linked character 

 both by the hen and by the -cock. Cock 



feathering develops in the hen-feathered 

 cock after castration, as well as in the hen 

 when old (according to a brief notice by 

 Darwin in " Animals and Plants," Chapter 

 XIII., Vol. 11, p. 29). The probable nature 

 of such an internal secretion is discussed by 

 Goodale in the following significant statement 

 (page 49) : 



The adjustment of the ovarian secretion to the 

 characters it modifies is very close, as shown by 

 the fact that the male characters produced in a 

 given female are like those of the corresponding 

 male. . . . Trom this we may conclude that the se- 

 cretion on the whole is relatively simple and prob- 

 ably of uniform nature. If the secretion were 

 composed of many substances, one to produce each 

 effect involved, such as the change from a vermic- 

 ulated feather to penciled, from a gray and white 

 to a black and brown, the resulting complexity 

 would be so great that one would not anticipate 

 any such close coordination as actually results. 

 For purposes of illustration we may assume that 

 the ovarian secretion is simple, producing its ef- 

 fect by oxidation or some other simple process. 

 The sort of result produced by oxidation, of 

 course, depends upon the substance that is oxidized. 



It need scarcely be added that this state- 

 ment furnishes no grounds for the identifica- 

 tion of the enzyme produced in the testes with 

 the factor or factors that represent it in the 

 sex chromosome, viz., the sex-determining 

 factors. It is possible, of course, that the 

 sex factors are enzymes, but there is not the 

 slightest warrant for drawing the conclusion 

 that they are (as some recent writers have 

 done) from genetic evidence of this kind, for 

 it is also possible that there may be a long 

 series of reactions between the chemical sub- 

 stance in the chromosome that we may iden- 

 tify if it pleases us to do so as the genetic 

 factor, and the enzyme that develops later 

 when the testes are formed. 



T. H. Morgan 



Columbia TJniveesitt 



SPECIAL ARTICLES 



THE BEHAVIOR OF CERTAIN GELS USEFUL IN 



THE INTERPRETATION OF THE 



ACTION OF PLANTS 



The amorphous carbohydrates constitute a 

 very important part of the colloids of the 



