44 PROBLEMS OF EVOLUTION 



that we have to postulate. But the latter factor accounts for 

 more in the case of the unicellular organisms than with the 

 Metazoa. Monads multiply by fission. Hence the last 

 generation belonged also to the first: they were fragments 

 of the individuals that existed at the outset. Thus each new 

 generation would be born with the maximum of acclimatisation 

 yet attained : there would be no delicate period of infancy. 

 But to speak of transmission seems out of place : except in 

 so far as Natural Selection comes in, we have here merely 

 the gradual acclimatisation of one individual. 



The Metazoa present still greater difficulties to the Lamarc- 

 kian. He has to account for the transference of any character- 

 istic the soma may acquire to the cells whose function is the 

 continuance of the species. But first let me put down a few 

 facts which may seem to tell in favour of the Lamarckian view. 

 Recent research shows more and more clearly the interdepen- 

 dence of the different parts of an organism. The liver, the 

 pancreas, the thyroid gland influence the nutrition of other 

 parts of the body. The reproductive cells do not live entirely 

 apart, but nourish the secondary sexual growths, such as, 

 in birds, accessory plumes. There have been instances of 

 cock-birds, in which only one testis had been developed, 

 having male plumage on the corresponding side and female 

 plumage on the other. 1 The reproduction of lost parts (e.g. 

 in crustaceans and in some kinds of reptiles) tells the same 

 tale. In any living organism one part depends upon other 

 parts and it would be untrue to say of the reproductive 

 cells that though they receive nourishment from the body, 

 they stand outside its organisation. There are other parts 

 correlated with them so that if they disappear or are re- 

 moved these other parts are no longer nourished and do not 

 develop. 



But if we concede so much, viz., that secondary sexual 

 growths can be shown to be dependent on the primary sexual 

 organs, we are still very far from allowing that any peculiarity 

 any part of the body may acquire can be transferred to the 



1 See Beddard, Animar Coloration p. 261. 



