1879.] Dr. Roberts. On a Milk-curdling Ferment. 157 



II. ' ; Note on the Existence of a Milk-curdling Ferment in the 



Pancreas." By William Roberts, M.D., F.R.S., Physician 

 to the Manchester Royal Infirmary. Received May 10, 1879. 



In the course of some observations on the digestion of milk by 

 extract of pancreas, I found that the milk passed through a more or less 

 pronounced phase of curdling, which often considerably delayed the 

 complete peptonising of the casein. As the property of curdling milk 

 has hitherto been regarded as the special appanage of the gastric 

 ferment, I was unprepared to find it also associated with the ferments 

 of the pancreas. There is, however, no doubt about the fact, at least 

 in regard to the pancreas of the pig, the ox, and the sheep. 



It was found that extract of pancreas made with saturated solution 

 of sodium chloride had much stronger curdling powers than the glyce- 

 rine extract, whereas the latter had stronger proteolytic powers than 

 the former. This indicates that the curdling ferment of the pancreas 

 is distinct from the proteolytic ferment (the trypsin of Kuhne), just as 

 it has been recently shown that the curdling ferment of the stomach is 

 distinct from pepsine. 



The brine extract of pancreas, or pancreatic rennet, as it may be 

 called, seems to act on milk exactly in the same way as rennet made 

 from the calf's stomach. It coagulates casein actively, both in neutral 

 and in alkaline milk, and it may be assumed as probable — at least until 

 further inquiry — that the curdling agent of the stomach and the 

 curdling agent of the pancreas are one and the same ferment. 



III. " On some Recent Improvements made in the Mountings of 

 the Telescopes at Birr Castle." By the Earl of Rosse, 

 D.C.L., LL.D., F.R.S. 



(Abstract deferred.) 



IV. " The Measurement of the Ratio of Lateral Contraction to 

 Longitudinal Extension in a Body under Strain." By A. 

 Mallock. Communicated by Lord Rayleigh, F.R.S. Re- 

 ceived May 17, 1879. 



The three coefficients which define the elastic properties of isotropic 

 solids, viz., the simple rigidity (n), Young's modulus (q), and the 

 elasticity of volume (h) are connected by the equations 

 2n ( f j J + l) = q = Sk (1-2/t). 

 The quantity jx or the ratio of lateral contraction to longitudinal 

 * extension, the measurement of which forms the subject of this paper, 



