218 METAMORPHOSES OP MAN 



staggers. On killing them and opening the crania, 

 Coenuri in various stages of development were found 

 in the brains. In point of fact, Kuchenmeister sowed 

 the Taeniae in the dog by feeding him on the Coenuri; 

 and the Coenuri in the sheep by feeding them on the 

 matured segments of the Taeniae. 



The advocates of spontaneous generation ask : 

 How, without our doctrine, do you explain the ex- 

 istence of so many intestinal worms, devoid of repro- 

 ductive organs, and appearing in the very heart of 

 the tissues, the muscles (cysticercus) and the brain 

 (coenurus) ? Thanks to the writings of the distin- 

 guished naturalists whose researches we have briefly 

 sketched, we can now reply : — These apparently aga- 

 mic species are various developmental phases of truly 

 sexual animals. In some instances, all the changes which 

 these beings undergo, in passing from the larval to the 

 perfect condition, have been observed, and analogy, 

 which becomes more forcible every day, justifies us in 

 believing that the same phenomena occur in the other 

 species also. 



This, therefore, is a result of much importance. 

 The final argument of the supporters of spontaneous 

 generation falls, to rise no more, and we may now, 

 with every certainty, repeat Harvey's dictum, " Omne 

 vivum ex ovo." Geneagenetic phenomena may mask, 

 but they never, in the main, alter this grand law. 

 We trust to be able to demonstrate this clearly in the 

 later chapters of this volume. 



