Boyal Society. 3zt> 



were deduced. The facts, he thinks, admit of a more natural ex- 

 phxnation, and one more consistent with the known jihysiulogical 

 laws of developement, by supposing the stain in the purity of the 

 mare's Arab blood to have arisen from the circumstance of an early 

 progenitor of the mare having belonged to the Eel-backed dun va- 

 riety, the peculiarities of which re-appeared in a later generation. 



8. " On the Structure and Functions of the Spleen." By Thomas 

 Gordon Hake, M.D. Communicated by Francis Kiernan, Esq., 

 F.R.S. 



The author, passing in review the various opinions which have 

 been advanced by anatomists respecting the intimate structure of 

 the spleen, arrives at the conclusion that hitherto only vague and 

 premature inductions have been made. It is generally admitted that 

 the fibrous envelope of this organ is formed of the external fibres of 

 the splenic vein ; and that from the internal surface of this envelope 

 fibrous prolongations are continued into the interior of its substance, 

 giving support to a fine cellular membrane, which is continuous with 

 their edges, and variously reflected so as to constitute cells. The 

 parenchyma, or solid structure of the spleen, everywhere accom- 

 panies these membranous productions, and forms the exterior walls 

 of the cells ; being composed of branches of the splenic arteries, of 

 the granular terminations of those arteries constituting the splenic 

 grains of Malpighi, of venules, which ramify around the splenic 

 grains, and of cellules, into which the venules open, and from which 

 the splenic veins take their rise. The author concludes, as the re- 

 sult of his inquiries, that a dilatable cellular tissue exists, containing 

 venous blood, between the granules within which the arteries ter- 

 minate, and the venules on the outeir side of the splenic grains : that 

 the venous membrane, which is continued from the cells to the 

 cellules, as well as to the venules, becoming more and more atte- 

 nuated, but without changing its essential structure, gradually loses 

 its tubular form, and resumes its primitive character of cellular 

 tissue ; and that the artery, in like manner, is limited in its distri- 

 bution within the granules by a cellular structure, which becomes 

 vicarious of it, and determines the function it has to perform. 



The author, in conclusion, offers some observations on the pro- 

 bable functions of the sj^leen. He considers the opinion which sup- 

 poses that organ to be distended, at particular times, with arterial 

 blood, as being completely refuted by the evidence derived from the 

 preceding account of its minute structure; and suggests the proba- 

 bility of the spleen being rather a diverticulum for venous blood. 



The paper is accompanied by seven highly finished drawings 

 illustrating the structures described. 



9. " Additional Experiments on the formation of Alkaline and 

 Earthy Bodies by chemical action when carbonic acid is present." 

 By Robert Rigg, Esq., F.R.S. 



The author gives a detailed account of several experiments in 

 which sugar, water, and yeast only w'ere employed, and from which 

 he deduces the conclusion that alkaline and earthy matters are form- 

 ed by chemical action. In one set of experiments, some of which 



