388 SHELL AN ORGANIZED BODY. 



ing that bloodvessels passed through the adductor muscles 

 of the bivalves to gain access to the interior of their valves. 

 Cuvier and Blumenbach favour the same opinion, because 

 " the oyster and muscle adhere to the shell, not only by 

 their muscles, but by the whole border of their cloak ;" and 

 because " the oyster has always between the two last strata 

 of the convex valve a considerable vacuity, which is filled 

 with a fetid acrid liquor, and which communicates with the 

 interior of the body by a particular aperture. " How," asks 

 Cuvier, " is this vacuity produced ? and, above all, how is it 

 removed upon the formation of each new stratum, if tlie 

 arterial and absorbent vessels do not penetrate into the 

 centre of the strata, to regulate its position, and to remove 

 from time to time the particles of the shell ?"* The Rev. 

 Dr. Fleming considered the vitality of shell to be demon- 

 strated from the changes which it undergoes when detached : 

 the plates of animal matter harden ; the epidermis dries, 

 cracks, and falls ofi^; and in many cases the colours fade, or 

 disappear. And what but vitality could have prevented 

 these changes previously ? The shells of the most delicate 

 of the Helicidse, which we must handle softly if we wish 

 to have them unbroken, preserve their vivid colours, their 

 pellucidity, and their integrity as long as the snail is 

 living, under whatever influences they are exposed ; but 

 no sooner have the shell and snail become sejjarate, than 

 the colour of the shell decays, its transj^arency becomes 

 dimmed, the epidermis shrivels or exfoliates, and the tex- 

 ture whitens and is rendered more friable. It is the pre- 

 sence of life in the shell that prevents this sad change, — 

 a low degree of life that, as John Hunter said, might exist 

 in animal substances devoid of apparent organization and 

 internal motion, and wherein the power of preservation 

 was simply required. 



The opposite opinion prevailed, and shell was all but 

 unaiiimously reckoned an inorganic structure}- until within 

 these few years, when its organism was amply proved by 



* Comp. Anatomy, i. 119. Trans. The cavity itself is difficult to find, 

 and escaped my observation in some attempts made to discover it ; but I am 

 informed, by a very skilful anatomist, that it is to be found on the anterior 

 part of the shell, at the edge. The communication between it and the body 

 of the fish must be exceedingly minute, perhaps impervious, for no oyster- 

 eating acquaintance of mine has any knowledge of the fetid fluid. 



+ " The shells themselves are absolutely deprived of vitality, permeated 

 by no vessels, and as incapable of expansion by any internal power as the 

 rocks to which they are not uncommonly attached." — Jonks' Anini, King- 

 dom, 385. 



