70 PROFESSOR LANKESTER. 



ferent vascular apparatus and fluid of the Hirudinea is associated. 

 Taking thus a comparative view of the .blood and blood-vessels 

 of the Chffitopoda, Gegenbaur was led, es})ecially by a considera- 

 tion of the condition of the Leeches, where (with the exception ot 

 Branchiobdella) the vascular system and perienteric system are 

 in open communication, to attach little importance to the re- 

 corded presence or absence of corpuscles in the blood (vascular 

 fluid) which he held to be only a portion of the general liquid 

 of the body cavity which had been gradually difl'erentiated. 



Professor Huxley, in his ' Manual of the Anatomy of In- 

 vertebrated Animals, 1877/ p. 219, writing of the oligochsetous 

 Chretopoda, says, " In addition (to the colourless cor])Usculated 

 fluid of the perivisceral cavity) there is a system of pseud-hscmal 

 vessels like those of the leeches, provided with contractile walls, 

 and containing a red, non-corpusculated fluid. No communica- 

 tion has been ascertained to exist between these vessels and the 

 perivisceral cavity ; but there can be little doubt that, as in the 

 case of the leeches, they must be regarded as a specially differen- 

 tiated part of the general system of the perivisceral cavity." 

 l^urther on (p. 223), in the course of an admirable description 

 of the anatomy of the Earthworm, he say, " A colourless fluid, 

 containing colourless corpuscles, and answering to the blood of 

 other invertebrated animals, occupies the perivisceral cavity ; but, 

 in addition to this, there is a deep-red fluid, devoid of cor- 

 puscles, which fills a very largely developed system of pseud- 

 hsemal vessels.^' 



In a book entitled ' Forms of xVnimal Life,' published at 

 Oxford in 1870, by Dr. George RoUeston, Professor of Phy- 

 siology in that University, there are two references to the 

 presence and absei;ceof corpuscles in the vascular system of Annu- 

 late worms. At page 124? the writer states that the vascular 

 system of the Earthworm "is called ' pseud- haemal,' because, 

 though the fluid which it contains is coloured and probably 

 respiratory in function, it is not corpusculated, and, therefore, 

 not morphologically blood." The morphological definition of 

 ' blood' here assumed is clearly another one than that adopted 

 by Gegenbaur. By Gegenbaur the specialisation of a portion of 

 the general body-cavity (coeloin) and its contained fluid fdf 

 respiratory or nutrient Junctions or both, in the form of a distinct 

 system of vessels coexii^tent with the undiU'erentiatcd portion, is 

 regarded as the formation of 'blood-vessds' and 'blood.' By 

 Dr. George llolleston the ])resence of corpuscles in the difTeren- 

 tiated fluid is held to be necessary in order that it may rightly 

 be called 'blood.' Ti\e second reference to this subject in this 

 physiologist's treatise is on page cxxix, and scarcely tends to 

 ex})lain the importance which he attaches to a strict morpholo- 



