262 lotsy's theory of evolution. 



characters as diploid individuals of the same species. We 

 know that diploid prothalli of ferns may produce ripe sexual 

 organs (even motile spermatozoids with the usual chemotactic 

 reactions). The majority of hereditary tendencies may, there- 

 fore, be carried by half the number of chromosomes, and different 

 sets of characters may be carried if the full number of chromo- 

 somes is present. As far as we can tell, the nuclei in the second 

 case mentioned are sporophyte-nuclei, yet something must have 

 happened to them to make the production of the prothallus 

 possible, although it is a prothallus in which sexual reproduc- 

 tion is impossible. To my mind the assumption of an internal 

 rearrangement of the essential components of the protoplasm 

 is sufficient to make these facts intelligible, however far from 

 an explanation this may be. The advantage of Lotsy's view, 

 according to him,* consists in creating an analogy between the 

 living and non-living world. He says : 



Roughly speaking, the " genes " correspond to the elements, the con- 

 stant species to the constant compounds; and just as the constant com- 

 pounds can only form with one another new compounds if separating- their 

 elements, so also the constant species can only form new species if in 

 reproduction the system of " genes " fall apart, and with other disinte- 

 grating systems of "genes" (Gciieiicoiiiplcxe) form new compounds of 

 "genes" which represent new constant species in so far as they are or 

 become homozygous. 



However, I venture to think that if the analogy is closely 

 examined, it does not bear out Lotsy's contention, and yet if it 

 could be strictly insisted upon, it would bring certain facts int(^ 

 stronger light. If a disaccharide is hydrolised, and by addition 

 of water two molecules of hexoses are formed, no separation 

 into the elements takes place. Moreover, the properties of the 

 elements as such bear no direct relation to the properties of the 

 compound from which we started, and the compounds at which 

 we arrive, and yet the compounds amongst themselves are what 

 we might call different species of the same genus. This point 

 need not be laboured further. It can be illustrated by innumer- 

 able similar facts taken from organic chemistry. Now. if we 

 assume that the protoplasm of a species is composed of a 

 definite chemical compound or a series of them united in a 

 hitherto not understood manner, we arrive at the notion of con- 

 stant species, or, to put it more precisely, of relatively constant 

 species, and I do not see any difficulty in explaining with this 

 assumption the existence of Jordan's units and of species in 

 the ordinary sense. The protoplasm, as stated before, must be 

 something different from the enzymes to which nowadays most 

 of the vital activities of plants and animals are ascribed. In 

 plants glucosides and appropriate enzymes do not exist in the 

 same cells, so normally there is no decomposition. They are 

 l:)rought together should the cellular structure be damaged, and 

 in some instances during germination. 



* Op cit. 3S3. 



