342 Dr Williams on the Blood-proper and 



secondly, the now generally admitted inadequacy of any theory of 

 Inflammation, which does not regard a modification of the affinities 

 peculiar to life, and here termed vital, as the primary and essen- 

 tial change, in the matter concerned in that process.* 



On the Blood-proper and Chylo-aqueous Fluid of Inver- 

 tebrate Animals. By Thomas Williams, M.D. 



In this paper the author, as stated in the Official Report on it 

 in the Proceedings of the Royal Society for March 1852, has accu- 

 mulated numerous observations, founded upon dissection and micro- 

 scopic inquiry, to prove that there exist in invertebrate animals two 

 distinct kinds of nutrient fluids ; that in some classes of this sub- 

 kingdom, these two fluids co-exist in the same organism, though 

 contained in distinct systems of conduits, while in others they become 

 united into one. The author proposes to distinguish these two 

 orders of fluids under the denominations of the blood-proper and 

 chylo-aqueous fluid. The former is always contained in definitively 

 organised (walled) bloodvessels, and having a determinate circula- 

 tory movement ; the latter with equal constancy, in chambers and 

 irregular cavities and cells communicating invariably with the peri- 

 toneal space, having not a determinate circulation, but a to-and-fro 

 movement, maintained by muscular and ciliary agency. He then 

 adduces evidence, derived from dissection, in proof of the statement 

 that the system of the blood-proper does not exist under any form, 

 the most rudimentary, below the Echinodermata ; that, in other 

 words, the system of the true blood, or of the blood-proper, begins 

 at the Echinodermata. The author then shews that below the 

 Echinodermata, namely in the families of Polypes and Acalephse, 

 the digestive and circulatory systems are identified, and that conse- 

 quently the external medium is admitted directly into the nutrient 

 vessels. He considers that this circumstance constitutes a funda- 

 mental distinction between the chylo-aqueous system and that of the 

 blood-proper, into which, under no conditions, is the external inor- 

 ganic element directly introduced. 



He conceives that his observations suffice to establish the law, with 

 reference to the chylo-aqueous fluid, that in every class in which it 

 exists, it is charged more or less abundantly with organised cor- 

 puscles. This is an invariable fact in the history of this fluid. His 

 inquiries shew that these corpuscles are marked by distinctive mi- 

 croscopic characters, not in different classes and genera only, but in 

 different species, entitling these bodies to great consideration in the 

 establishment of species. 



The paper then proceeds to demonstrate the proposition, that in 



t Proceedings of the Royal Society of Edinburgh. Session 1851-2. 



