286 NOTES. 



are totally opposed to its vital properties, and cannot co-exist with 

 them), when united into the form of cyanate of ammonia. If we 

 were only acquainted with those elements as they exist in organic 

 compounds, their transposition into a crystaline salt would be almost 

 as marvellous to us as the opposite change is now. If this latent 

 organizability or vitality be admitted (as we conceive logical proof 

 to have been given that it must) as a property of a large proportion 

 of what we call inorganic matter, is there any such wonderful diffi- 

 culty in imagining that it may be brought into play in some other 

 manner than by the agency of a pre-existing germ ? We think not. 

 But let further investigation and more extended experience decide." 

 British and Foreign Medical Review, January, 1845. 



(53.) See a pamphlet circulated by Mr. Weekes in 1842. For a 

 detail of further and more conclusive experiments, reference may be 

 made to Explanations, forming a Sequel to Vestiges, &c. 



(54.) The writer of the critique upon this work in the British 

 and Foreign Medical Review, after saying that " none of the easy 

 solutions which have been offered of the difficult problem presented 

 by the appearance of this acarus, can be admitted," proceeds to make 

 a few remarks much to the above purpose ; and adds " Not the 

 least curious part of its (the acarus's) history is the series of 

 metamorphoses which it undergoes before quitting the solution ; 

 these being entirely different from the very slight changes which 

 other acari undergo after their emersion from the egg. Further, we 

 believe it may be positively asserted, that, in whatever mode these 

 acari are first generated, it is not from eggs ; since, after they have 

 escaped from the solution, they live in the neighbourhood, and 

 readily breed ; and their eggs, which we have ourselves seen, are 

 quite large enough to have been readily visible in the solution, had 

 they existed there." 



The metamorphoses here adverted to will perhaps go some way to 

 satisfy those who have objected that the acarus, belonging, as it 

 does, to the articulata, is too high an animal to have been produced 

 otherwise than from ova. 



I would, nevertheless, remark that the Acarus Crossii is only 

 brought forward as one illustration, and in order that a hypothesis 

 which I think has strong probabilities on its side may have the 

 benefit of any doubts that can be instituted with regard to the pro- 

 duction of this creature. The decision of the question against the 

 conclusion here leant to, would still leave much sound illustration, 

 and not in the least affect the general argument. 



(55.) The objections made to the idea of a parity between ad- 

 vancing organization and the succession of fossils are all in regard 

 to subordinate points, and either rest on assumptions as to the 

 grades of animals which are entirely without solid foundation, or take 

 hold for a feeble support of certain blanks and imperfections in the 

 geological record. 



