RESPIRATION IN THE CHELONIA. 3 



tion has led some physiologists to explain this important function upon principles 

 inconsistent with sound physiology, analogy, or experience. Perault attributes the 



expansion of the lungs, and consequent inspiration, to the elasticity of the mem- 

 branes forming their cells; and the expiration to the compression of muscles, of 

 which, he says, these animals have plenty. " Apparement," he says, "il est neces- 

 saire de supposer que Pinspiration se fait par le ressort des ligamens durs et fermes 

 qui composent les mailles qui out etc decrites: en sorte que lorsque les muscles qui 

 peuvent comprimer le poumon viennent a sc relacher, les ligamens s'etendent et 

 elargissant les ouvertes de toutes les vessies augment la capacity de tout le poumon." 

 Varnier boldly asserted that the whole process of respiration, both expiration as 

 well as inspiration, was effected by the lungs themselves alone, by the means of 

 their muscular texture, as a muscular network surrounded them, by which means 

 they could respire by the alternate dilatation and contraction of the vesicules with- 

 out the aid of the other instruments of respiration. He says, " Je parvins a me 

 demontrer a moinieme que le poumon de la tortue etoit entoure d'un reseau mus- 

 culaire (pie par ce moyen ils etoit parfaitement irritable, qu'ils avoit une action 

 propre, independente des autres agens de la respiration et qu'ils pouvoit inspirer 

 par lui mSme;" and soon after adds, "le muscle du poumon de la tortue qui produit 

 un mouvement convulsive," and then says that, "dans le tortue le poumon est cel- 

 lulaire; les cellules se correspondent comme dans la grenouille; le muscle enveloppe 

 toute la masse, et en se contractant la remue toute entiere ;" and concludes his 

 memoire by saying, "le poumon est un organ actif; qu'il est le premier et le prin- 

 cipal agent de la respiration, et que cette fonction depend, comme dans les amphibies, 

 de la dilatation et contraction alternative des vesicules qui determinent altemative- 

 ment la contraction des muscles inspirateurs et cxpirateurs, et cela independamment 

 de la volonte." Admitting the lungs to possess this muscular texture, which could 

 not be perceived by Haller and the best anatomists, they would still be ill adapted 

 to innate by their own power. *We learn, through the Transactions of the lloyal 

 Academy of Paris, that it was the opinion of Monsieur Tauvry that they breathed 

 only in walking. " La tortue est enfirmee entre deux ecailles immobiles, et elles 

 n'a d'ailleurs aucun diaphragme qui puisse servir a une compression alternative des 

 poumons. Dans cette difficult^ d'expliquer sa respiration, Monsieur Tauvry s'est 

 avise d'en rapporter la cause an mouvement du marcher; quand la tortue est en 

 repos, sa t!te et ses pies sont retires sous l'ecaille superieure, et la peau qui l'enve- 

 loppe entierement est plisse, mais quand l'animal marche, il pousse au dehors sa tete 

 et ses pies ; sa peau s'etend, puisqu'elle est tiree par ces parties, et par consequent 

 elle forme interieurement un plus grand cspace, et e'est clans cet espace vuide que 

 l'air cxttrieur est oblige d'entrer." This explanation, which is very anomalous 

 with everything we know of this function in other animals, I put to the test of the 

 following experiments, which proved it erroneous. I took the Testudo orbicularis 

 in its contracted state, and wrapt it up in paper, binding it all round with bandages 

 so fast, that the testa and sternum were brought so near before as not to admit the 

 exit of the head. I then made an aperture in the paper opposite to its nose, and 

 thus deprived of every motion, I placed it before the name of a candle, yet I found 

 n. >t onlv that it blew the flame, but sometimes so strongly as nearly to extinguish it. 



