FOREWORD 9 



vestigations they were devoted to a cognate subject 

 namely, Heterogenesis at which I had pre- 

 viously worked in 1870-1872. Heterogenesis is 

 the name applied to processes by which living 

 things arise from the matter of pre-existing organ- 

 isms belonging to a totally different species. Or, 

 in other words, as I have defined it, it is : the 

 production from the substance of organisms or 

 their germs of alien forms of life." These in- 

 vestigations resulted in the publication, towards the 

 end of 1903, of a large fully-illustrated work, en- 

 titled Studies in Heterogenesis, in which many 

 facts were recorded and views expressed at variance 

 with commonly received biological doctrines. 



One set of examples may be cited. If the 

 reader were to refer to the index of that volume 

 he would see after the word " Amoeba? ' that 

 there are references to descriptions of about five- 

 and-twenty different modes in which I have seen 

 such organisms forming from the substance of 

 other vegetal or animal matrices. Thus I have 

 seen Amoeba? taking origin from the protoplasm 

 of some of the cells of Moss radicles, from the sub- 

 stance of encysted Euglense, from the eggs of 

 different kinds of Rotifers, from Vaucheria rest- 

 ing-spores, from encysted Ciliates, and from the 



