BIO-DYNAMICS 77 



ancestor was once possessed of an excretory system. The 

 Nematode worms, which are mostly parasitic, and which, 

 according to Prof. J. A. Thomson, " do not seem to lead on to 

 anything else," are characterised by many startling features. 

 " It is very interesting," says this leading biologist, "that the 

 only animal types without wandering phagocytes are the 

 Nematode worms (some of which, at least, have stationary 

 phagocytes) and the Lancelets." (Absence of work with 

 absence of symbiosis !) The parasitism of the Nematodes is 

 frequently carried so far that in the resulting retrogression 

 from the ancestral type no mouth or digestive system is repre- 

 sented. As soon as we come to the few free-living forms, we 

 find that the ancestral features, such as a distinct mouth, a 

 digestive canal and a vascular system of canals, can be 

 recognised. Darwin noted in the Origin of Species that the 

 hair-claspers of parasitic mites (Acaridce) " could not have been 

 inherited from a common progenitor." He says that " these 

 organs must have been independently developed," but it did 

 not apparently occur to him that this " independent " develop- 

 ment was due to a vital departure from strenuous and symbio- 

 genetic ancestral dynamics in favour of recent parasitic, and 

 therefore anti-symbiotic dynamics. He did not perceive how 

 vital a change from positive to negative dynamics is involved 

 in every change from bio-economic strenuousness to sluggish- 

 ness. Yet volumes could be written to demonstrate this truth 

 by facts drawn from every class of organisms. Among the many 

 conspicuous and puzzling features marking the change 

 from ancestral symbiotic to later anti -symbiotic dynamics, I 

 would mention excessive reproduction and excessive growth of 

 reproductive and nutritive paraphernalia, excessive metamor- 

 phosis, excessive sexual dimorphism, excessive liability to 

 hyper-parasitism, excessive development of parts of the nutri- 

 tive apparatus all these features more or less at the expense 

 of high developments, e.g., of brain. All these developments, 

 I assert, must be classified as pathological, although hitherto 

 this has been only partially recognised. That is to say the 



