640 



Oedogonium resulting in the formation of four carpospores we are 

 not dealing with a case of reduction of the number of chromosomes? 

 And if that were the case, could the four carpospores by any stretch 

 of the imagination be homologised with the four blastoraeres of 

 Amphioxus? 



My critic expresses his opinion that an antithetic alternation of 

 generations among Metazoa is undemonstrable ^). His statement to 

 this effect is perhaps excusable by the circumstance that he holds to 

 "a very different and possibly clearer interpretation of the relations 

 between metaphytic and metazoan reproductive processes than that of 

 Beard" 2). But, may I ask, has Prof. Mac Millan ever considered 

 the facts of Comparative Embryology in the light of a possible alter- 

 nation? Has he ever for himself examined one single type of animal 

 development with a view to the elucidation of this question, or with 

 a view to showing a close relationship between metaphytic and meta- 

 zoan modes of reproduction ? That one who has worked and pondered 

 over curious phenomena in the development of fishes during a period 

 of upwards of seven years should decline to accept Prof. Mac Millan's 

 opinion as conclusive may, on reflection, appear to him to be reason- 

 able, and, when he considers that there was a time ^) in the history 

 of Botany, when in the highest plants an antithetic alternation was 

 undemonstrated, and apparently as undemonstrable as one such in 

 Metazoa may now appear to him to be, he may come to see that 

 the latter part of his criticism of an earnest attempt to throw light 

 on the phenomena of animal reproduction was as fallacious as the 

 earlier portion. 



The theory of an antithetic alternation of generations in animals 

 has not been enunciated by me without much thought and labour, and 

 without duly weighing the responsibility of such action. There are 

 difficulties to be encountered, but these are less due to a super- 

 abundance than to a lack of facts in certain cases. I know the 

 weaknesses *) of the theory, and — what is more encouraging — I know 

 its strength. That it would meet with much unfavourable criticism 

 was to be foreseen, that it might even be abused by scientific men 



1) 1. c. p. 441. 



2) 1. c. p. 443. 



3) Before 1851. 



4) By „weaknesses'' it is intended to say that at present there exist in 

 zoology, as in botany, numbers of special cases, where the life-histories 

 have been too incompletely worked out to admit of their inclusion in any 

 scheme or law of development. 



