Specific Heat of certain Rocks. 169 



i-ated, the diaplu-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 the 

 liver of Carcinus mcenas, 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 process 

 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, \^^f 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 Secretary. 



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

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

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

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

 results of the thermometi-ic experiments on subterranean tempera- 

 ture. In order to eliminate the ellcct of specific heat, M. llegnault 

 of Paris (well known by his experiments on this subject) undo°rtook. 



