Brown . — Studies in the Physiology of Parasitism . IV. 495 
less than that present in the original turnip extract. This is shown by the 
following table of activities : 
M 2 = 1 M 2 S' = 1 M 2 M 2 ' = 0.75 M 2 T = 0.58 
S = 1 SS' =0.8 SM/ =0-2 ST =0.13. 
2. Amount of crystalloids present . This can be determined by estima- 
tion of the osmotic pressure. This was done by finding what concentration 
of a cane-sugar solution balanced the given solution on the opposite side of 
an osmometer. The osmometer consisted of a semi-permeable collodion 
thimble with capillary tube attached. 1 
The figures were : 
Turnip extract balances 0-43 molar cane-sugar. 
^2 >> >5 0*29 ,, ,, )f 
S 5, 0*03 ,, „ „ 
General Discussion of above Results. 
Enzymic preparations of two types can be obtained from a fungal 
culture, viz. (1) watery extracts of washed and triturated mycelium, and 
(2) the fluid in which germination has taken place. The activity of the 
preparation obtained has been shown to be dependent upon (1) the density 
of sowing of the spores, (2) the time allowed for germination and growth, 
and (3) the nature of the nutrient medium. 
Fluid in which germination has taken place . With any given con- 
centration of spores, the enzymic activity increases to a maximum with 
lapse of time, and subsequently falls off. When the spores are sown thinly, 
the absolute value of the maximum reached is diminished, and its attain- 
ment takes place at a longer interval from the time of sowing. 
These enzymic solutions are characterized by the high concentration 
of enzyme present. They also contain an amount of retarding substances 
comparable with, but somewhat less than, that of the original nutrient 
medium. 
Mycelial extract . In the case of thick sowings of spores, the curve of 
activity was shown to rise during the first day’s growth, and then to decline 
after about the second day. In the case of the thin sowings in Erlen- 
meyer flasks, only the latter part of the curve was obtained. It is obvious 
1 An air-dried collodion thimble is placed in 50 per cent, alcohol in water for 24 hours, then 
washed in water till the alcohol is retnoved. The open end of the thimble is then dried in the air 
and sealed by means of a solution of collodion to the rubber cork through which the capillary tube 
passes. The junction is then allowed to dry completely in the air, when the osmometer is ready for 
use. This osmometer is permeable to simple salts like chlorides and nitrates of the monovalent 
metals, but not to sulphates or salts of bivalent metals such as barium chloride, &c. For a full 
account of the technique of preparing membranes of graded permeability, see papers by the writer 
in Biochemical Journal, vol. ix, 1915, p. 591, and vol. xi, 1917, p. 40. 
