74 Mr J. S. Langley, On the estimation of ferment [Feb. 21, 



February 21, 1881. 



Professor Newton, President, in the Chair. 



T. H. Corry, Gonville and Caius College, F. R. Weldou, St John's 

 College, and W. Heap, were balloted for and duly elected associates 

 of the Society. 



The following communication was made to the Society : 



On the estimation of ferment in gland-cells by means of osmic 

 acid. By J. N. Langley, M.A., Fellow of Trinity College. 



A few years ago Nussbaum 1 observed that such ferments as he 

 could obtain stained rapidly with osmic acid. Iu consequence of 

 this observation he made many others upon the staining power 

 with osmic acid of ferment-producing glands. He arrived at the 

 conclusion that the depth of staining with osmic acid was a satis- 

 factory indication of the ferment-content of gland-cells. 



Mr Langley briefly reviewed the facts that have been brought 

 forward for 2 and against 3 Nussbaum's method and conclusions. 

 He contended : — 



That the cells of different glands do not increase in staining 

 power in proportion to the amount of ferment that can be obtained 

 from them. 



That the cells of any one gland do not increase and decrease 

 in staining power as the cells increase and decrease in various 

 physiological states in ferment-content. 



That there is no obvious correspondence between the depth of 

 staining with osmic acid of extracts of ferment-producing glands 

 and the amount of ferment contained by the extracts. This point 

 was illustrated by experiments. 



From these facts it follows that the depth of staining with 

 osmic acid of any gland-cell is not a satisfactory indication of the 

 power of the cell to produce ferment. 



There are very few physiological substances which, when iso- 

 lated, reduce osmic acid readily. Those that have this action, 

 such as bile acids, haemoglobin and peptone, do not, as far as Ave 

 know, occur in living gland-cells ; this taken together with the 

 fact that glandular tissues diminish in staining power when they 



1 Nussbaum, Archiv f. Mik. Anat. Bd. xni. S. 716, 1877. 



2 Nussbaum, Archiv'f. !(/&. Anat. .Bd. xv. S. 119, 1878; Bd. xvi. S. 513, 1871). 

 Edinger, Archiv f. Mik. Anat. Bd. xvn. S. 193, 1879. 



3 Griitzner, Pfluger's Archiv, Bd. xvi. S. 122, 1877; Bd. xx. S. 39/5, 1879. 

 Langley, Foster's Jour. Physiol. Vol. n. p. 271, 1879. 



