168 H. §. H. WARDLAW. 
that the portions coming down first were very rich in 
cellular material, consisting for the greater part of cells 
resembling leucocytes but derived from the epithelium of . 
the mammary gland (Hewlett, Villar and Revis, 1909; 
Ernst, 1913). 
Subtraction of the total protein of the deposit from the 
total organic material shows the presence of 19% of non- 
nitrogenous organic matter. The clear superfluid from the 
caseinogen precipitation showed a powerful reducing action 
towards Fehling’s solution, indicating the presence of a 
reducing body (lactose?). The percentage of lactose in the 
deposit was estimated by Pavy’s method, caseinogen being 
first removed by precipitation with acetic acid, and the 
solution being boiled. In this way 16% of lactose was 
found to be present in the deposit. The Pavy’s solution 
was Standardised against a standard solution of Merck’s 
lactose (C,:H».Oy + H.O) of approximately the same reducing 
power as the solution of the deposit. 
Fat was tested for by allowing the deposit to stand under 
petroleum spirit for twenty-four hours, then pouring off the 
petroleum spirit and evaporating to dryness in a weighed 
vessel. No residue was left after volatilisation of the spirit. 
Fat is therefore apparently not present in the deposit in 
weighable amount. The microscopic examination of the 
deposit showed the presence of a certain number of granules 
which stained with osmic acid and Sudan III. 
6. Solubility of the Deposit in Water. 
When the deposit obtained from milk by spinning it in a 
centrifuge is shaken up in a volume of water equal to that 
of the milk from which it was removed, a considerable 
portion of it goes into solution. The following table gives 
the amounts of the total deposit and of the potential ash | 
which may be dissolved in this way. 
