HAEMOCYANIN. PERIVISCEEAL FLUID. 



[BOOK i. 



increases to 73 C. ; coagulation actually occurs at 74 C. They are 

 likewise coagulated by alcohol, ether, mineral acids, and glacial acetic 

 acid ; and give the general reactions of the proteids. 



Haemocyanin is a colloid, non-crystallizable body ; in addition to 

 it there appears to be no proteid or proteid derivative in the blood. 

 When decomposed with mineral acids it yields a prismatic crystalline 

 body. 



It was said that the blue colouring matter of the blood of the 

 Octopus was contained in the liquor sanguinis. The blood does 

 contain a small number of corpuscles, but these are colourless. 



The following table, extracted from Frederique's memoir, exhibits the 

 results of the quantitative analyses hitherto made of the blood of 

 Cephalopoda. 



On certain coloured corpuscles found in the Perivisceral Fluid of 

 certain Sea-urchins and Holothurians. 



The perivisceral fluid of Sea-urchins and Holothurians has a more or less 

 distinct reddish tinge, which is due to the admixture of a considerable 

 proportion of coloured corpuscles 1 . These are large nucleated amoeboid 

 cells, of which the fluid endosarc is filled with small highly refracting 

 spherules of a rich mahogany-brown colour. They abound in the water- 

 vascular system and in the intestinal blood-vessels of the Urchin, and 

 are also to be found scattered throughout all the tissues, more particularlv 

 the integument. The following observations have been made by Mr 

 Patrick Geddes and have been kindly communicated by him to the Author. 



If an Urchin be divested of its spines and left exposed to the air, 

 its warm hue soon becomes dingy, and, in the course of a few hours 



1 For descriptions and figures of these corpuscles see 



Erdl Wiegmann's Archiv, 1842. 



Williams, On the Blood-proper and Chylaqueous Fluid of Invertebrate Animals. 

 Philosophical Transactions, 1852. Part n. p. 595. 



Semper, Eeisen im Archipel der Philippinen, Bd. i. Taf. xxxui. 



Hoffman, Niederl. Archiv, 1871. 



Geddes, " Observations sur le fluide pe'riviscerale des Oursins." Archives de 

 Zoologie experimental, 1878. 



