﻿T. Davidson — What is a Bnichiopocl ? 271 



stronger wish causes him to reject tlie most plausible support, if be 

 has reason to suspect that it is vitiated by error. Those to whom I 

 refer as having studied this question, believing the evidence offered 

 in favour of ' spontaneous generation ' to be thus vitiated, cannot 

 accept it. They know full well that the chemist now prepares from 

 inorganic matter a vast array of substances which were some time 

 ago regarded as the sole products of vitality. They are intimately 

 acquainted with the structural power of matter as evidenced in the 

 phenomena of crysttillization. They can justify scientifically their 

 belief in its potency, under the proper contlitions, to produce organ- 

 isms. But in reply to your question they will frankly admit their 

 inability to point to any satisfactory experimental proof that life can 

 be developed save from demonstrable antecedent life." Further on 

 he adds, " In fact, the whole process of evolution is the manifesta- 

 tion of a Power absolutely inscrutable to the intellect of man." 



Darwin's tempting and beautiful theory of descent with modifica- 

 tion bears a charm that appears to be almost irresistible, and I would 

 be the last person to assert that it may not represent the actual 

 mode of specific development. It is a far more exalted conception 

 than the idea of constant independent creations ; but we are stopped 

 by a number of questions that seem to plunge the conception in a 

 maze of inexplicable, nay, mysterious difficulties ; nor has Darwin, 

 as far as I am aware, said how he supposes the first j)rimordial form 

 to have been introduced. The theory is at best, as far as we can at 

 present perceive, with our imperfect state of knowledge, but half 

 the truth, being well enough in many cases as between species and 

 species ; for it is evident that many so-termed species may be nothing 

 more than modifications produced by descent. It applies, likewise, 

 to accidental variations as between closely allied genera, yet there is 

 much more than this, with respect to which the theory seems in- 

 sufficient. The strange geological persistency of certain types, such 

 as of Lingula, Discina, Nautilus, etc., seems also to bar the at presev.t 

 thorough acceptance of such a theory of general descent with 

 modification. Barrande seems to be strongly opposed to the 

 Darwinian view, for in his admirable memoir already quoted he 

 states: "Par contraste nous devons constater, comme resultat final 

 de nos etudes, que I'observation directe contredit radicalement toutes 

 ses previsions des theories paleontologiques au sujet de la com- 

 position des premieres phases de la faune primordiale Silurienne. 

 En efi'et, I'etude speciale de chacun des elements zoologiques qui 

 constituent ces phases, nous a demontre, que les previsions theoriques 

 sont en complete discordance avec les faits observes par la paleon- 

 tologie. Ces discordances sont si nombreuses, et si prononcees que 

 la composition de la faune reelle semblerait avoir ete calculee a dessin, 

 pour contredire tout ce que nous enseigne les theories, sur la pre- 

 miere apparition et sur revolution primitives des formes de la vie 

 animale sur le globe." 



We have no positive evidence of those modifications which the 

 theory involves, for types appear on the whole to be permanent 

 as long as they continue, and when a genus disappears there 



