165 



minate, and the venules on the outer 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 spleen. 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 were 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 

 were made in silver, others in china, and others in glass apparatus, 

 after the vinous fermentation had gone on during five days, the 

 quantity of ashes obtained was, in the silver apparatus eighteen, in 

 the china nineteen, and in the glass fifteen times greater than the 

 previous quantity. A further examination of these ashes showed 

 that they consisted of potass, soda, lime, and a residue not acted 

 upon by muriatic acid. The author states that, however irrecon- 

 cilable to our present chemical knowledge this important conclusion 

 may at first sight appear, yet when it is taken in connexion with 

 the decomposition of other vegetable matter, and with the pheno- 

 mena which accompany the growth of plants, it may not excite sur- 

 prise ; and may be regarded as in harmony with the phenomena of 

 natural science. He concludes by offering suggestions towards ex- 

 tending the inquiry into the subject of the formation of bones of 

 animals by the action of the powers inherent in their organization. 



10. " On the Difference of Colour in different parts of the Bodies 

 of Animals." By James Alderson, M.A., M.D., late Fellow of Pem- 

 broke College, Cambridge. Communicated by P. M. Roget, M.D., 

 Sec. R.S., &c. 



The hypothesis advanced by the author in explanation of the well- 

 known partial absence of the coloured pigment or rete mucosum, in dif- 

 ferent parts of the human body, and that of other animals, is that it 

 is due to the union or adhesion of the epidermis and the true skin, 

 so as to exclude the rete mucosum. He supports this hypothesis by 

 the analogy of a cicatrix, which is the result of an organization of a 



