639 



in which the subsequent reduction may be effected, there can be no 

 doubt of its existence. 



I must decline to follow Prof. Mac Millan at any length in his 

 dissertation on palingenetic and caenogenetic spores. A limitation in 

 the use of prefixes to the word spore would be far more welcome 

 than any such fanciful classification. Palingenesis and caenogenesis, 

 or their adjectives, are as meaningless expressions in botany as in 

 zoology. They lacked stamina in their very birth, for they came into 

 the world without credentials. There exists no criterion, except in 

 the imaginations of those who believe in them, as to which is the one 

 and which the other, and the frequency with which they are mistaken 

 for each other ought to lead to their lapse into obscurity. 



But it may be of interest to submit the example given by Prof. 

 Mac Millan to closer analysis. 



On p. 441—442 he compares the formation of four caenogenetic 

 carpospores of Oedogonium with the (artificial) separation of four 

 blastomeres of the segmenting egg of Amphioxus, and, although 

 the one is a natural and the other an artificial occurence, on p. 441 

 he describes the products of the two as homologous ! The objection 

 that in the latter case we are dealing with experimental results, 

 which have no natural counterparts in the animal kingdom, may be 

 waived. It may, perhaps, suffice to note that in the Amphioxus 

 example we know exactly all details of the nuclear condition of the 

 blastomeres, or, rather, that we can infer them from other cases, 

 whereas we are in absolute ignorance concerning, and can infer with 

 no absolute degree of certainty, what takes place in the nuclei during 

 the two divisions which result in the formation of four carpospores. 



We are entitled to say that in the Amphioxus instance, if we 

 look upon the fertilized egg as an individual, — and we have every 

 right to do so, — in the artificial separation of four blastomeres we 

 have practically performed two fissions, and thus have given rise to 

 four individuals. Can we regard the two divisions of the zygote to 

 form four carpospores as two such simple fissions? From what we 

 know of the number four, i. e. of two consecutive divisions giving 

 rise to four products, in both kingdoms, we are bound, at any rate, to 

 be cautious whenever we meet with something of that kind ; for, how- 

 ever slight our knowledge may be, it is sufficient to warrant our 

 attaching some importance to two consecutive cell-divisions resulting 

 in the formation of four products and followed by a pause. In other 

 words, what justification has Prof, Mac Millan for assuming, and 

 this he virtually does, that in the two divisions of the syngamete of 



