489 



of an animal life -cycle. Fundamental errors of embryology have 

 hitherto prevented the recognition of this. But, just as there is a 

 science of normal development, waiting patiently for recognition in our 

 universities, one whose continued neglect and exclusion will continue to 

 revenge itself upon mankind — as it has already done in the past 

 — by a corresponding retardation of priceless knowledge, so there is 

 also — a branch of the foregoing, and only to be understood in the 

 light of it — an important science of abnormal embryology, largely 

 represented by the tumours and their problems, a knowledge of which 

 can only be advanced by aiding and fostering the former. 



For the elucidation of the tumours two sciences are necessary, 

 pathology, a daily more and more feted and endowed branch of 

 learning, and embryology, the science of the coming-into-being of 

 life, at present the handmaid of many sciences, and almost without 

 a habitation to call its own. This despised and rejected branch of 

 human knowledge is in importance to mankind second to none. With- 

 out its light much possible knowledge is enshrouded in thick, pitchy 

 darkness, without it one momentous portion of pathology can have 

 no scientific existence. This is well shown by the explanation now 

 offered of the nature, the etiology, of the tumours. The facts, estab- 

 lished by the researches of pathologists, more especially those due to 

 the brilliant work of Wilms upon the mixed tumours, may be con- 

 sidered in the light of comparative embryology. 



The tumours form a series of parasites, comparable to, for in- 

 stance, the Eulima-series of snails parasitic upon starfishes and 

 other echinoderms. In these all gradations from highly organised 

 snails down to mere sacs of eggs and sperms are encountered. In 

 like manner, as particularly Wilms 1 ) has shown, there are all gra- 

 dations from the highest embryomata, or more or less rudimentary 

 embryos (which in the upward direction pass gradually into identical 

 twins), through others with embryonic organs, even brain, windpipe, 

 gut, etc., down to the simple forms of tumours, of but one form of 

 tissue, a connective tissue or an epithelium. 



Summing up, and taking W t ilms as the leading exponent of the 

 one side, the divergences between his views and mine work out as 



1) Wilms has conclusively demonstrated, that, for example, all 

 gradations from a highly organised embryoma down to a simple sarcoma 

 may be met with. In adopting his pathological conclusions, I regret 

 to be unable to endorse any of his later embryological ones, or Bonnet's 

 derivation of embryomata from polar bodies (! ! !), or cleavage products, 

 not identified by Bonnet and Wilms as primary germ-cells. 



