SECRETION OF DIASTASE BY PENICILLIUM CAMEMBERTII 235 
At the outset of the investigation it was found that a considerable 
amount of experimentation would be necessary in order to obtain 
adequate methods of research. It was necessary to devise a new 
method for measuring starch digestion. It was also essential to 
determine the significance of the number of spores sown in its bearing 
on the rate of digestion, as well as the effect of various kinds of distilled 
water on the rate of digestion. Rather extensive data were obtained 
in the preliminary experiments, of which only the salient facts are 
presented. 
Methods and Materials 
Glassware. — The vessels used in these experiments were all of 
Jena glass. They were first cleaned with soap and water and chromic 
acid cleaning mixture, rinsed well with tap water and distilled water, 
and finally rinsed with the water used in the experiments. 
Chemicals. — The chemicals were all of high grade, either Baker's 
analyzed or Merck's highest purity. The starch used was Merck's 
soluble starch, which is prepared from potato starch according to 
Lintner's method as described by Allen (1909). A solution of this 
starch, when the solvent is redistilled water, permits a small amount 
of growth of Penicillium camemhertii. This would seem to show that 
the starch contains traces of mineral nutrients. According to Ford 
(1904 A), such a preparation contains phosphate, and perhaps organic 
phosphorus, which cannot be completely removed. According to 
Thomas (1914), also, the phosphorus present in purified samples of 
starch is in organic combination. 
Water. — The laboratory distilled water, which is derived by distil- 
lation from an iron boiler and which is stored in a block tin tank, 
contains a dark brown precipitate when the last few liters in the tank 
are drawn. This precipitate consists of some form of iron. The 
water showed by test with Nessler's reagent no ammonia, and by the 
diphenylamine reaction no nitrates. Redistilled water was prepared 
by the double distillation of this water from Jena glass flasks con- 
taining acid and alkaline potassium permanganate. This method is 
described by Jones and Mackey (1897). Water treated with carbon 
black was prepared by adding 90 grams of moist carbon black, G Elf 
brand, to 4 liters of distilled water, allowing it to stand for three hours 
with occasional shaking, and then filtering. 
On comparing the growth of Penicillium camemhertii in a solution 
