vin BIOGENESIS AND ABIOGENESIS 259 



and the com are parts of the living body, which 

 have become, to a certain degree, independent and 

 distinct organisms. Under the influence of cer- 

 tain external conditions, elements of the body, 

 which should have developed in due subordination 

 to its general plan, set up for themselves and 

 apply the nourishment which they receive to their 

 own purposes. 



From such innocent productions as corns and 

 warts, there are all gradations to the serious 

 tumours which, by their mere size and the 

 mechanical obstruction they cause, destroy the 

 organism out of which they are developed ; while, 

 finally, in those terrible structures known as 

 cancers, the abnormal growth has acquired powers 

 of reproduction and multiplication, and is only 

 morphologically distinguishable from the parasitic 

 worm, the life of which is neither more nor less 

 closely bound up with that of the infested 

 organism. 



If there were a kind of diseased structure, the 

 histological elements of which were capable of 

 maintaining a separate and independent existence 

 out of the body, it seems to me that the shadowy 

 boundary between morbid growth and Xeno- 

 genesis would be effaced. And I am inclined to 

 think that the progress of discovery has almost 

 brought us to this point already. I have been 

 favoured by Mr. Simon with an early copy of the 

 last published of the valuable " Reports on the 



