xxviii INTRODUCTION. 



known that the lobster will live for a long time out of 

 water, provided the branchiae are occasionally bathed, so 

 as to keep them in a humid condition, whilst it will 

 die very soon on being confined in a small quantity of 

 water, without access to air. 



There has been considerable discrepancy in the state- 

 ments of different anatomists respecting the circulation in 

 the Crustacea. Messrs. Audouin and Milne Edwards* 

 have considered that " no other than the two great bran- 

 chial veins terminate in the heart, and, consequently, only 

 pure aerated or arterial blood is propelled by it over the 

 general system ; the circulation is, in fact, the same as in 

 the Gasteropodous Mollusca ; the ventricle is exclusively 

 systemic, and is provided with only two venous aper- 

 tures." Such is a summary of their opinion. The fact, 

 however, that the circulation is of a mixed kind was evi- 

 dently known to Hunter, and has been elaborately demon- 

 strated by Professor Owen in his more recent researches.f 

 A reference to the engravings from the Hunterian draw- 

 ings in the collection of the Royal College of Surgeons,! 

 to that of the heart of the lobster by Professor Owen in 

 his lectures above referred to, and to the respective de- 

 scriptions of these figures, will show " that the heart, 

 instead of being purely systemic, is partly branchial, and 

 impels the blood, not through the body only, but also to 

 the respiratory organs." 



* Recherches Anatomiques et Pliysiologiques sur la Circulation clans les 

 Crustaces. Ann. des Sc. Nat. t. ii. 



t Lectures on the Comparative Anatomy and Physiology of the Invertebr. 



J Catalogue of the Physiological Scries of Comparative Anatomy contained 

 in the Museum of the Royal College of Surgeons, vol. ii. Copied in Professor 

 I! yiner Jones's " Animal Kingdom," pp. 333-336. 



