490 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8, 
Austrian pine, dock, daisy, goldenrod, ragweed, rye, and timothy pollens 
were tested with the different substrates for lipase. The tests with ethyl 
butyrate were unsatisfactory. In the olive oil emulsion and methyl acetate 
media, Austrian pine, dock, ragweed, and rye pollens gave positive tests 
for lipase. The action on methyl acetate was especially marked with Aus- 
trian pine pollen, in which case the titrations showed nearly double the 
amount of acid with fresh pollen as compared with the boiled control. 
Tests for Proteolytic Enzymes 
Substrates for Proteolytic Enzymes 
I. Blood fibrin. Fresh fibrin from pig's blood was obtained at the 
slaughter house, and was washed for several hours with a stream of cold 
water to remove corpuscles. Fairly uniform and compact strands of the 
fibrin were selected, and portions as nearly equal as possible were placed 
in test tubes with lo cc. of distilled water, plugged with cotton, and sterilized 
for 20 minutes in an autoclave. Other portions were stained with I percent 
Congo red and the color was fixed by immersion in boiling water. The 
red color is liberated when the fibrin is digested. The colored fibrin was 
also sterilized. 
Table 13. Fermi's Gelatin Test 
5 cc. Fermi's gelatin, 5 cc. H2O, 100 mg. pollen, 37° C. Degrees of liquefaction or 
failure to solidify, after standing in ice water 10 minutes, indicated by signs. 
Kind of Pollen 
Unheated Pollen 
Autociaved Pollen 
24 Hrs. 
48 Hrs. 
24 Hrs. 
48 Hrs. 
I. Apple 
+ 
+ + 
+ 
+ 
+ 
+ 
+ 
5. Dock 
+ + 
+ + + 
6. Elm 
+ 
+ + 
+ 
+ + 
8. Lily, Easter 
+ + 
+ + + 
+ + 
+ + 
10. Pine, Austrian 
+ 
+ + + 
II. Pine, white 
+ 
+ + 
+ + + 
+ + + + 
13- Rye 
+ + 
+ 
+ 
15. Magnolia 
+ + 
+ + + 
• 
16. Maple, Norway 
+ 
+ 
2. Fermi's gelatin. The proportions used were those given by Dernby. 
700 grams of gelatin were dissolved in 1,250 cc. of hot water over a water 
bath, strained through cheese cloth, and 2 grams of finely pulverized thymol 
were added. The solution was diluted to 2 liters and sterilized. Dernby 
diluted further before using, but this was not found necessary with the 
pollen extracts. When the gelatin was used it was melted over a bath and 
