381 



horn of the lateral ventricle, and the peculiar disposition of cerebrai 

 substance constituting the hippocampus minor, but the conditions 

 in which they have been found at so many distinct points of the 

 series, appear to lead almost irresistibly to the following conclusions : 



1. That these parts, so far from being (as has been stated by some 

 anatomists) peculiar to the human brain, are common to man and 

 the whole of the Quadrumana, including even the lowest forms. 



2. That they attain their maximum of development in species 

 which do not belong to either extremity of the series. 



3. That in the lower forms their diminution takes place chiefly 

 in the antero-posterior direction, corresponding with the reduced 

 length of the posterior cerebral lobes, the greater part of which is 

 occupied by them. 



4. That in the higher forms they are narrower in proportion to 

 their length, and bear a smaller ratio to the surrounding mass of 

 cerebral substance. 



5. That the extreme of the last condition is met with in man, 

 where these parts are also characterized by their variability in size 

 and form, want of symmetry on the two sides, and frequent rudi- 

 mentary condition, or even entire absence. 



XIX. " On Liquid Transpiration in relation to Chemical Com- 

 position." By THOMAS GRAHAM, Esq., V.P.R.S., Master 

 of the Mint. Received June 20, 1861. 

 (Abstract.) 



In accordance with the analogy of the transpiration of gases, the 

 passage of liquids under pressure through a capillary tube is spoken 

 of as liquid transpiration. The subject owes the development which 

 it has already attained chiefly to the investigations of M. Poiseuille. 

 The precision of the mode of experimenting pursued by that phy- 

 sicist has been remarked on by every one who has engaged in the 

 inquiry. The same method was accordingly adopted with little 

 variation in the present investigation. 



The isolated observation made by M. Poiseuille, that alcohol di- 

 luted to different degrees is most retarded in passing through a ca- 

 pillary tube at that degree of dilution where the greatest condensa- 

 tion of the mixed liquids occurs, was understood by the author as 

 indicating that the definite hydrate of alcohol containing six equiva- 



