Speci/ic Heat of certain Rocks. 169 



rated, the diaplii'agm dissolves or gives way, the cells burst, and the 

 secretion flows along the ducts, the acinus disappearing, and mak- 

 ing room for a neighbouring acinus, which has in the mean time 

 been advancing in a similar manner. The whole parenchyma of 

 glands of this order is thus, according to these observations, in a 

 constant state of change, — of development, maturity, and atrophy, — 

 this series of changes being directly proportional to the profusenets 

 of the secretion. 



In the second order of glands, the follicular, as exemplified in tho 

 liver of Cardniis mtenas, the germinal cell or spot, is situated at the 

 blind extremity of the follicle, and the secreting cells, as they ad- 

 vance along the follicle, become distended with their peculiar secre- 

 tion. 



Among other general conclusions deducible from these observa- 

 tions, it appeared that ducts are to be considered as intercellular 

 passages, into which the secretions formed by cells are cast. 



Finally, the author inferred from the whole inquiry, 1, That se- 

 cretion is a function of the nucleated cell, and takes place within it ; 

 and, 2. That growth and secretion are identical — the same procets 

 under different circumstances. 



April 4. — Sir T. M. Brisbane, Bart., President, in the 

 Chair. 



1. On the Theoretical Investigation of the Absolute Intensity 



of Interfering Light. By Professor Kelland. 



2. On the Quarantine-Classification of Substances, with a 



View to the Prevention of Plague. B^ John Davy, 

 M.D., F.R.S., L. & E. 



3. Results of Experiments on the Specific Heat of Certain 



Rocks. By M. Regnault of Paris. Communicated by 

 the Secretai'y. 



Professor Forbes observed, that, in his communication to the Royal 

 Society on the Conductivity of Soils for Heat, on the 20th Decem- 

 ber last (see Proceedings, page 343*), he had referred to the sepa- 

 ration of the conductivity and specific heat, which are involved in the 

 results of tlie thermometric experiments on subterranean tempera- 

 ture. In order to eliminate the effect of specific heat, M. Reonault 

 of Paris (well known by his experiments on this subject) undertook, 



