196 THE POPULAR SCIENCE MONTHLY. 



able, because their appearance under such circumstances would not 

 amount to a proof. The absolute proof of spontaneous generation 

 must come from the formation of living organisms out of inorganic 

 matter. If Infusoria are generated in solutions of organic matter, 

 independently of spores or germs, the question may be fairly raised 

 whether we do not begin the experiment with materials in which life 

 already exists, even though this material is not in the form of distinct 

 organisms." Now, these last few lines, as they at present stand, tend 

 to convey to the reader very erroneous impressions, and yet I am 

 aware that views of the same kind are very commonly expressed, and 

 seem to exist in an inchoate or half-realized form in the minds of 

 many distinguished persons. It is for this reason, and on account of 

 the authority attaching to Prof. Wyman's statements, that I am in- 

 duced to take notice of this particular passage in order to attempt its 

 rectification. 



In the first place, then, under the old term, " spontaneous genera- 

 tion," are included two processes quite distinct from one another 

 namely, Heterogenesis and Archebiosis. With regard to Hetero- 

 genesis, this is merely the opposite of Homogenesis : and the latter is 

 the name for that mode of generation or reproduction among living 

 things which is looked upon with most respect and which is most 

 generally known. It is the process by which "like produces like," 

 that is, where the offspring grow into beings like their parents. In 

 Heterogenesis, on the other hand, we have the birth of dissimilar 

 products, the beginning of a new branch from a "life-tree," in which 

 the offspring have no tendency to assume the parental type. This 

 occurs, for instance, where the protoplasmic matter of an animal or of 

 a vegetal cell becomes modified and resolved into Bacteria. Here we 

 have to do with the mere transformation of living matter. It can, 

 therefore, only take place where living matter preexists. And seeing 

 that many, among whom I may especially mention Needham, 1 Pouchet, 

 and Trecul, have, both now and formerly, understood by the phrase 

 spontaneous generation merely such a process of metamorphoses of liv- 

 ing matter as is implied by the term Heterogenesis, it is very misleading 

 to say that "the absolute proof of spontaneous generation must come 

 from the formation of living organisms out of inorganic matter." 



It seems obvious, however, that, when Prof. Wyman wrote this 

 passage, he, forgetting the more common acceptation of the phrase 

 " spontaneous generation," must have used it in the same sense as I 

 now employ the term Archebiosis in the sense, that is, of life-origina- 

 tion. But, even taking it in this sense, how far, we may ask, is Prof. 

 Wyman justified in saying that its proof " must come from the for- 

 mation of living organisms out of inorganic matter ?" 



The statement is, in my opinion, one which cannot be logically 

 entertained by a believer in the ordinary physical doctrines of life, and 



1 See "The Beginnings of Life," vol. i., pp. 246-252, and vol. ii., p. 181. 



