174 REPORT — 1851. 



the interposition of the peritoneal fluid between the blood-proper and the 

 external medium. 



The history of the remarkable fluid element of nutrition, as now described 

 in the Annelida, will henceforth enable the physiologist to understand how 

 intimately and immediately necessary to the maintenance of the vital actions, 

 the influence of the surrounding medium must be in these inferior orders of 

 animals ; how instantaneous the death when transferred into fresh water, and 

 how important the part must be which the mineral and saline ingredients of 

 sea-water perform, in preserving the integrity of the voluminous organic 

 fluids of the body. 



Blood-proper. — When Cuvier first constituted the Annelida into an inde- 

 pendent class, he attached great importance to the discovery of red blood in 

 these animals, and this fact became the ground of his classification : " Frappe 

 de la couleur si remarkable du liquide nourricier, chez ces animaux, il les 

 designa d'abord sous le nom de Vers a sang rouge." Lamarck, no less than 

 Cuvier, was impressed with a sense of the important significance of red blood 

 iu the animals to which he now applied the name of Annelides ; like Cuvier, 

 he viewed the red blood as the essential distinction of the class*. 



M. de Blainville now discovered that in Aphrodita Herissa the blood was 

 coloiirkssf. Pallas, however, had in fact anticipated both Cuvier and De 

 Blainville in this discovery, and also in that of the existence of red blood 

 in the Annelida generally t. 



To the laborious researches of Milne-Edwards, the zoologist is indebted 

 for a full and complete history of the colour and distribution of the blood in 

 the Annelida§. But it is a remarkable circumstance that so searching an 

 observer should have overlooked the question aflfecting the microscopic cha- 

 racters of this fluid. After stating that in the EunicidcB, Euphrosinida, Ne- 

 reides, Nephthys, Glycera, Ojionidce, Arenicola, Hermellce, Terebellce, Ser- 

 pulce, Lumbrictis and Hirudo, the blood is of a red colour, he remarks, " Mais, 

 du reste, examine au microscope, ce liquide ne m'a pas semble difl'erer du 

 sang des autres animaux sans vertebres. Les globules qu'on y voit nager 

 n'ont pas du tout I'aspect de ceux propres au sang des animaux vertebres : ce 

 sont des corpuscules circulaires dont la surface a une apparence framboisee, 

 et dont les dimensions varient extremement chez un ineme animal." 



In the passage cited, this eminent author admits the existence of circular 

 corpuscles in the blood of the Annelida, Avhich according to his account pre- 

 sent the appearance of raspberries, varying much in dimensions in the same 

 individual ||. In his excellent memoir in the Philosophical Transactions^, 



* " Ce qui a effectivement paru tres singulier, ce fut de trouver que les Annelides, quoique 

 moius perfectionnes en organisation que les Mollusques, avaient cependant le sang veritable- 

 nient rouge, tandis qui depend de son etat et de sa composition, et qui est celle du sang de 

 tous les animaux vertebres. On sent bien que, parmi les animaux que nous rapportons a 

 noti'e classe des Annelides, ceux qui si trouveraient n'avoir pas dans leur organisation le 

 caractere classique, n'infirment point ce caractere et ne sont places ici qu'en attendant que leur 

 organisation soit mieux connue." — Lamarck, Animaux sans Vertebres, t. v. p. 276. 



t Art. Vers, du Dictionnaire des Sciences Naturelles, t. Ivii. p. 409. 



X See his Miscellanea Zoologica, p. 89. " Sectis in dorso longitudinaliter tegumentis, 

 occurrit vasculum lympha sfepe turbidula plenum : " from tliis sentence it is much more pro- 

 bable that in this section Pallas merely opened the great cavity between the intestine and in- 

 tegument, out of which the "IjTupha turbidula" escaped, and that it was not the blood-pro- 

 per, as Milne-Edwards supposes, but the peritoneal fluid which Pallas saw. 



§ Annal. des Sciences, 2™^ serie, Oct. 1838, ' Circulation dans les Annelides,' par M. H.M 

 Edwards. 



II Recherches pour servir a I'histoire de la circulation du sang chez les Annelides, lues a 

 1' Academic des Sciences le 30 Oct. 1837. 



^ ' The Blood-corpuscle considered in its different Phases of Development in the Animal 

 Series,' by T. W, Jones, F.R.S. &c., Phil. Trans, part 2. 1846. 



