Januabt 8, 1909] 



SCIENCE 



67 



correct, it seems to negative the assump- 

 tion. 



Although, therefore, many of the facts 

 of animal parthenogenesis harmonize with 

 the naive assumption that the presence of 

 one X-element means the male tendency, 

 of two such elements the female tendency, 

 we are not yet in a position to assert that 

 this is . always the case ; and the problem 

 may be complicated by the presence of 

 factors still unknown. We are led to 

 suspect that this is really the case by the 

 apparent disjunction of the sexual tend- 

 encies that occurs in the formation of the 

 asexual spores of plants. Botanical cytol- 

 ogists are agreed, I believe, that such 

 spores develop with the reduced or haploid 

 number of chromosomes, yet they may pro- 

 duce either males or females. This seems 

 irreconcilable with the view that half the 

 spores contain an X-element which is lack- 

 ing in the other half. But we are led, 

 nevertheless, to suspect from the facts 

 known in animals that the male-producing 

 spores may be characterized by the absence 

 of some element that is present in the 

 female-producing ones; and the detailed 

 study of the chromosomes has given us so 

 many cytological surprises in recent years 

 that we may well await more intimate 

 acquaintance with the facts in the plants 

 before drawing any definite conclusion in 

 this case. 



I can only touch here upon the possible 

 relation of hermaphroditism to the phe- 

 nomena seen in dieeious forms. If the 

 hermaphrodite condition were a synthetic 

 one, formed by the union of male and 

 female tendencies that are separately borne 

 as such by the gametes, a serious difficulty 

 would be presented to the provisional 

 formulation that has been suggested. But 

 it seems clear from the experiments of 

 Correns and others that hermaphroditism, 

 at least in the higher plants, should not 

 thus be conceived. Hybridization experi- 



ments seem to prove that the hermaph- 

 rodite tendency is borne as such by all the 

 gametes, so that the heredity of hermaph- 

 roditism is closely similar to that of the 

 spotted or "mosaic" type of coloration in 

 animals. The hermaphrodite character is, 

 in other words, a unit character which does 

 not split into separate male and female 

 tendencies in the gametes. There seems, 

 accordingly, to be as much reason to pos- 

 tulate in this case a special "hermaphro- 

 ditic factor" which liberates both sexual 

 capacities, as a special mosaic or mottling 

 factor in the case of mosaic pigmentation. 

 I have no desire to spin hypotheses, but 

 will suggest that the same general view as 

 that suggested for the dieeious forms can 

 be applied to the hermaphrodite if we as- 

 sume that all the gametes alike contain an 

 X-element and in addition an "hermaph- 

 roditic factor" which enables both male 

 and female characters to come to ex- 

 pression." It can, I think, be shown that 

 the results of Correns 's crosses can be in- 

 terpreted in the terms of such an assump- 

 tion; but it does not seem worth while to 

 speculate in this direction until more is 

 known of the facts.^^ 



I wish very distinctly to say that in any 

 ease I should only regard the naive formu- 

 lation of the facts here outlined as a provi- 

 sional one which may have no other value 



"How little we yet know of the true nature of 

 hermaphroditism is shown by the Marchals' re- 

 sults on the dioecious mosses. The hermaphrodites 

 artificially produced by regeneration from the 

 sporogonial tissue are in this case evidently syn- 

 thetic, since they are formed by the union of 

 separate male and female " tendencies " ; but such 

 liermaphroditism would seem to be of quite dif- 

 ferent nature from that of normally hermaphro- 

 ditic species. The same experiments prove that 

 there may likewise be two forms of males and 

 females; for the apparently male or female plants 

 produced by regeneration from the sporogonial 

 tissue are potential hermaphrodites (as is proved 

 by their regenerative offspring) and differ widely 

 in this respect from the normal males and females. 



