CKYPTOGENESIS, PARTHENOGENESIS 211 



syngonic nemas? Proof of the existence of this form of genesis, for which I have 

 suggested the name cryptogenesis.* will place parthenogenesis in a new light. 

 Evidence for or against cryptogenesis should be sought in the structure and be- 

 havior of the "oocytes" and "ova" of syncystic forms. From some forms of syn- 

 gony it would appear to be hardly more than a few steps along this road to par- 

 thenogenesis, itself perhaps, as it were, a waystation en route to cryptogenesis. 

 There have been three main theories of natural parthenogenesis: 



1. Owen's, that not all the germinal matter is necessary for the production 

 of the new organism, and that after the new organism has matured, a left over por- 

 tion of the germinal matter within it proceeds to develop new organisms. 



2. Huxley's, that the parthenogenetic "egg" is not in reality an ovum, and 

 that its development is comparable to the growth of an organism from a bud. 



3. Hertwig's, that parthenogenesis is a degenerate fertilization. 

 Parthenogenesis as commonly understood may be said to be of three kinds: 



a, The resultant generation is all female (homocystic). b, The resultant genera- 

 tion is all male (homocystic). c, The resultant generation is heterocystic. Fur- 

 thermore it may be divided into three cases: 



1. The parthenogenetic generation alternates strictly with a bisexual one. 



2. Several parthenogenetic generations occur between the bisexual ones. 



3. Pure syncysty; i.e., no reproduction other than parthenogenesis is known. 

 A common supposition is that the parthenogenetic gamete is an ovum or 



macrogamete pure and simple. It seems more difficult to explain the three kinds 

 of parthenogenesis on the supposition that the gamete of the parthenogenetic 

 organism is essentially or only an ovum or macrogamete, than on the supposition 

 that this gamete is syncystic ; for this latter supposition makes it easy to imagine 

 the different results of natural parthenogenesis to arise by processes similar to 

 those already familiar in heterocysty. 



Cryptogenetically considered even parthenogenesis may be conceived of as a 

 concealed, (often perhaps unseeable or at least hitherto unseen) but more or 

 less "normal" genesis. 



A strict construction of the phase of cryptogenesis discussed rests on the 

 supposition that what we have been calling parthenogenesis is one phenomenon, 

 and not a collection of more or less related phenomena. My own present view 

 is that this latter clause probably comes nearer the truth, and that partheno- 

 genesis as we have broadly understood it may possibly cover cases in accord 

 with most of the theories that have been proposed.** 



Cryptogenesis may not exhibit all the phases investigation has disclosed in 

 heterocysty; the suggestion is rather not only that all the results accomplished or 

 supposed to be accomplished in natural parthenogenesis may be explicable along 

 the lines of ordinary fertilization, but that parthenogenesis, and cryptogenesis 

 if it exist, is not so much a distinct method of generation, or even a degenerate 

 fertilization, as an evolved amphigony. 



There is a certain amount of evidence often interpreted as showing that 

 fertilization cannot be superimposed on parthenogenesis, e.g., parthenogenetic 

 eggs may "resist" sperm of the same species. In normal fertilization once an egg 

 entered by a spermatozoon it thereafter "resists" the entrance of other sper- 

 matozoa. If what we have been calling parthenogenesis is, in any given case, 

 in reality cryptogenesis, then the parthenogenetic eggs may be regarded as 



* This conception differs from earlier ones in its space-and time-limits, (time, antecedent; space 

 the confines of ancestral gonic colls), and in that its methods and mechanism are extended to possibly 

 include all the phases known for, or postulated of, the forms of genesis from wnich it is supposed to ho 

 evolved. 



** Here we seem unconsciously dominated by our terminology, some of which is outgrown and, as ap- 

 plied, even misleading. The facts and ideas need critical analysis, as well as the benefit of an adequate 

 terminology, as Sir E. Ray Lankester has just indicated in the August number of "Nature" (1917). 



