335 
Bokorny (61) has also pointed out that between protoplasm and 
the enzymes there are certain striking similarities. Toward temper- 
ature, he says, it has long been known that the enzymes conduct 
themselves like protoplasm. His table, setting forth these analo- 
gies so far as the influence of temperature and light are concerned, 
is given in the following : 
( r 
Name of protoplasm or enzyme. Action of temperature, light, etc. 
Protoplasm of bacteria and fungi. . . 
Yeast 
Lower plants and animals 
Zymase (yeast) 
Maltase or glucase 
Invertase (from yeast) 
Diastase (of malt) 
Emulsin 
Myrosin 
Pepsin (from the stomach) 
Trypsin (from pancreas) . . 
Papain (vegetable trypsin) 
Rennin 
Catalase (Loew) 
Laccase (Bertrand) 
Nageli found the spores of bacillus subtilis could be heated 11 
hours in boiling water without showing the slightest damage. 
In the vegetative state this organism is largely destroyed by 
heating to 55°-60° C. 
Light tends to destroy many bacteria. 
Direct sunlight destroys by long exposure. 
A temperature of 25°-30° C best for the development of yeast. 
Young vegetative yeast-cells are killed at 50°-60° C., spores at 
60°-65° C. In the dry state yeast withstands 125° C. 
Spirogyra killed in water at 45°-50°.a Many algae live in the 
Carlsbad thermal springs, temperature 53° C. Some forms of 
algae have been found in thermal springs having a temperature 
of 85° C. 
Salt-water amcebas are killed at 35° C, fresh-water amcebas at 
40°-45° C. 
Strong light is harmful. 
Optimum temperature, 25° C, loses activity at 0° C, and is de- 
stroyed at 53° C. 
Yeast maltase destroyed at 55° C. Maize maltase actsbest at 35° C. 
Quickly destroyed whenmoist at 70° C, and at 50° C when heated a 
long time. Optimum temperature 31° C, according to Rjeldahl 
52°-56° C. 
Moist heat kills at 75° C after short exposure. Dry diastase stands 
100° C and over. -Optimum temperature 50°-55° C. 
Sunlight kills it. 
Optimum temperature 45°-50° C., destroyed at 70° C. In dry 
state stands 100° C. for hours. 
Inactive at 0° C, thermal death-point 85° C. 
In 0.2 per cent hydrochloric acid, optimum temperature 35°-40° C. 
Death-temperature, 55°-60° C. Dry, stands 160° C. for a short 
time. 
Optimum temperature 40° C., death-temperature 69°-70° C. In 
dry state can be heated to 160° C. without harm. 
Optimum temperature 40° C. Killed at 75° C. Dry, stands 100° C. 
Optimum temperature 40° C. Higher than 70° C. kills quickly. 
Death-temperature 72°-75° C. 
Optimum temperature 20° C. Destroyed at 60°-63°C (Yoshida). 
Destroyed at 70° C (Bertrand). 
a The water-plant Hottonia shows a maximum assimilation of carbon dioxide at 31° C. This is only 
one-fourth as strong at 50° C, and at 56° C it ceases altogether. 
PART II (2) CHANGES IN THE COMPOSITION OF MILK PRODUCED BY 
THE MILK ENZYMES. 
According to Marfan (1), milk is not an inactive fluid, but possesses 
properties wdiich are more or less characteristic of living tissues. For 
example, it gives Bordet’s reaction, namely, that when the milk of 
one species of animal is repeatedly injected into the blood of an 
animal of different species the blood serum of the animal so treated 
gradually acquires the power of coagulating milk in much the same 
way as rennin. (See P. T. Muller (2) ^ Vergleichende Studien Ueber 
die Gerinnung des Kaseins Durch Lab und Lactoserum.”) Human 
milk has been found by Moro (3) to have the powder of coagulating 
hydrocele fluid, whereas cow’s milk does not give this reaction. 
