T. Dacidson — Wliat is a Brachiopod ? 
271 
stronger wish causes liim to reject tbe most plausible Support, if be 
bas reason to suspect tbat it is vitiated by error. Tbose to whoin I 
refer as baving studied tbis question, believing tbe evidence offered 
in favour of ‘ spontaneous generation ’ to be tbus vitiated, cannot 
accept it. Tbey know full well tbat tbe cbemist now prepares from 
inorganic matter a vast array of substances wbicb were some time 
ago regarded as tbe sole products of vitality. Tbey are intimately 
acquainted witb tbe structural power of matter as evidenced in tbe 
phenomena of crystallization. Tbey can justify scieutifically tbeir 
belief in its potency, under tbe proper conditions, to produce organ- 
isms. But in reply to your question tbey will frankly admit tbeir 
inability to point to any satisfactory experimental proof that life can 
be developed save from demonstrable antecedent life.” F urther on 
be adds, “ In fact, tbe wbole process of evolution is tbe manifesta- 
tion of a Power absolutely inscrutable to the intellect of man.” 
Darwin’ s tempting and beautiful tbeory of descent witb raodifica- 
tion bears a cbarm tbat appears to be almost irresistible, and I would 
be the last person to assert tbat it may not represent tbe actual 
mode of specific development. It is a far more exalted conception 
than tbe idea of constant independent creations ; but we are stopped 
by a number of questions that seem to plunge tbe conception in a 
maze of inexplieable, nay, mysterious difficulties ; nor bas Darwin, 
as far as I am aware, said bow be supposes tbe first primordial form 
to bave been introduced. Tbe theory is at best, as far as we can at 
present perceive, witb our imperfect state of knowledge, but half 
tbe trutb, being well enougb in many cases as between species and 
species ; for it is evident that many so-termed species may be nothing 
more tban modifications produced by descent. It applies, likewise, 
to accidental variations as between closely allied genera, yet there is 
much more tban this, with respect to wbicb tbe tbeory seems in- 
sufficient. Tbe stränge geological persistency of certain types, such 
as of LingnJa, Discina, jYautilus, etc., seems also to bar tbe at present 
thorough acceptance of such a tbeory of general descent wirb 
modification. Barrande seems to be strongly opposed to the 
Darwinian view, for in bis admirable memoir already quoted be 
States : “ Par contraste nous devons constater, comme resultat final 
de nos etudes, que l’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 effet, l’etude speciale de cbacun 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 l’evolution primitives des formes de la vie 
animale sur le globe.” 
We bave no positive evidence of tbose modifications wbicb tbe 
tbeory involves, for types appear on tbe wbole to be permanent 
as long as tbey continue, and wben a genus disappears tbere 
