PHYSIOLOGY OF THE INVERTEBRATA. 233 



shell, bathing not only the legs themselves, but also the 

 inner coating of the valves. 



Dr. MacMunn has discovered the presence of histo- 

 hajmatin, myoha3matin, and enterochlorophyll in the organs 

 and tissues of the following Crustaceans : Hoiiiarus, Cancer, 

 Astacus, Carcinus, and Fagarus; consequently tissue-respira- 

 tion* is well developed in these animals. No doubt this 

 kind of respiration plays an important part in the land 

 crabs ; and. a priori, the respiratory pigments should be 

 more largely developed in these aaimals than in other 

 Crustaceans. 



The Activity of Eespiration. 



We owe to MM. Regnault, Reiset, and Jolyet nearly the 

 whole of our knowledge corncerning the ratio between the 

 carbonic anhydride exhaled and the oxygen absorbed in 

 the Invcrtehrata. The animals employed in these inves- 

 tigations were allowed to remain under a bell-glass for a 

 certain time ; and as the oxygen of the air was absorbed, a 

 similar volume of carbonic anhydride was admitted into 

 the apparatus. For an illustration and a description of 

 the apparatus used in these experiments the reader is 

 referred to Rechcrchcs Chimiques snr la Resinration dcs 

 Animaux des diverses Classes by Hegnault and Reiset, or to 

 the late Dr. A. Wiirtz's TraiU de Chimie Biologiquc, pp. 422, 

 434, and 440. 



The table on p. 234 represents the results obtained by 

 these French savants. 



Concerning the figures it may be remarked that among 

 the bivalve Mollusca the weight of the shell naturally 

 diminishes the proportion of oxygen absorbed, when this is 

 reported as the gross weight of the animal. 



* See also a recent paper on " The Respiration of Cells in the Interior of 

 Masses of Tissue," by M. H. Devaux, in Comptes Jiendus, vol. 112 [1891]. 



