163 



the barometer, of the moon when similarly situated with reference 

 both to its superior and inferior passage. In a column of this table 

 are given the results of two years' observations at St. Helena, ex- 

 tracted from Colonel Sabine's paper. From a comparison, it appears 

 that the effect produced by the moon on the barometer at Singapore, 

 nearly on the equator, is slightly greater than at St. Helena, more 

 distant from it by 14^° of latitude. 



March 18, 1852. 



COLONEL SABINE, R.A., V.P. and Treas., in the Chair. 



A paper was read, entitled, " On the Blood-proper and Chylo- 

 aqueous Fluid of Invertebrate Animals." By Thomas Williams, 

 M.D. Communicated by Thomas Bell, Esq., Sec. R.S. &c. Re- 

 ceived Dec. 18, 1851. 



In this paper the author has accumulated numerous observations, 

 founded upon dissection and microscopic 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 coexist in 

 the same organism, though contained in distinct systems of con- 

 duits, while in others they become united into one. The author 

 proposes to distinguish these two orders of fluids under the denomi- 

 nations of the blood-proper and chylo-aqueoiis fluid. The former is 

 always contained in definitively organized (walled) blood-vessels, 

 and having a determinate circulatory movement; the latter, with equal 

 constancy,inchambers and irregular cavities and cells, communicating 

 invariably with the peritoneal space, having not a determinate cir- 

 culation, but a to-and-fro movement, maintained by muscular and 

 ciliary agency. He then adduces e\ddence, 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 Echino- 

 dermata ; that, in other words, the system of the true blood, or of 

 the blood-proper, begins at the Echinodermata. The author then 

 shows that below the Echinodermata, namely in the families of Polypes 

 and Acalephse, the digestive and circulatory systems are identified, 

 and that consequently the external medium is admitted directly into 

 the nutrient fluids. He considers that this circumstance constitutes 

 a fundamental distinction between the ch3do- aqueous system and 

 that of the blood-proper, into which, under no conditions, is the ex- 

 ternal inorganic 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 organized 

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

 His inquiries show that these corpuscles are marked by distinctive 

 microscopic characters, not in diflrerent classes and genera only, but 



