310 The Unity of the Organism 



blance of the offspring to the parent tends to be very com- 

 plete, and the reason for like producing like is no puzzle, 

 while the scparated-off j)ortion is a representative sample 

 of the Avhole organism." '^ 



One would like to know liow Professor Thomson would 

 reconcile the first statement with the sum total of facts of 

 reproduction. We know from his numerous books that few 

 biologists are more broadly learned on the subject of or- 

 ganic reproduction than he. It is therefore hardly possible 

 that he would hesitate to admit that if a complete census 

 were made at this hour of the individual organisms compos- 

 ing the living world, the enumeration taking note of all 

 individuals produced sexually and all those produced asex- 

 uall}^, the asexually produced would probably exceed in 

 numbers those produced by the other process. And be it 

 remembered that in some of the most prolific sub-divisions 

 of the bacteria, the dinoflagellates, the diatomes, the try- 

 panosomes, the sarcodinians, various groups of algae, and 

 even some of the liigher plants and insects, sexual reproduc- 

 tion, with rare exceptions, has never been seen. 



Nor should one fall to recall that in the many groups of 

 both plants and animals where sexual and asexual repro- 

 duction alternate in the same species, the individuals pro- 

 duced asexually are almost, if not always, far more numer- 

 ous tlian those produced sexually. So far as numbers of 

 individuals are concerned all zoologists know how small a 

 part sexual propagation plays in some of the coelenterates, 

 as the coral-])roducing poly[)s; in most bryozoa ; in several 

 grou])s of tunicates ; and in some fiat-worms. If one ob- 

 jects that coral polyps, bryozoan polypides, and ascidian 

 zooids ought not to be counted as "individuals," the reply 

 sufficient for the present discussion is that whatever they 

 should or should not be called they are what give rise to the 

 sex-cells, the things which are central in the theories of* 

 heredity. "Germinal continuity," so fundamental in tliese 



