oct 30,1916 Growth of Parasitic Fungi in Concentrated Solutions 
259 
is a question which can not be answered from the data now at hand. 
Potassium nitrate has been used extensively as a plasmolyzing agent for 
determining osmotic pressure in plants. 
Fischer (5) reaches the conclusion, however, that the protoplasts of 
bacteria are readily permeable to this salt. True (17) used cane sugar in 
his work on species of Spirogyra, and it has been used to a considerable 
extent by other investigators. Calcium nitrate is not commonly used 
as a plasmolyzing agent. 
From the concentrations of glucose which were found to be favorable to 
the growth of fungi it seems probable that this substance penetrated the 
protoplasm, perhaps quite readily. It is, of course, probable that all 
the substances penetrate into the cell to some extent. It is possible that 
the protoplasm of the fungi here used is readily permeable to the salts 
and sugars employed in this study and that they can pass into the cell 
until the concentration within is the same as without. Then the presence 
within the cell of some substance to which the protoplasm was imperme¬ 
able would raise the osmotic pressure within above that of the surround¬ 
ing solution, and the fungus could grow. 
The importance of this ability of parasitic fungi to grow in solutions 
which are capable of exerting a high osmotic pressure is evident. 
Whether this ability is due to the osmotic pressure in the fungus being 
originally higher or whether it becomes higher through a diffusion of 
substance into the hyphae, or whether there is an actual increase in the 
osmotically active substances within the cell, as Eschenhagen concludes, 
or whether other factors than a high osmotic pressure enable fungi to 
remain turgid and grow in concentrated solutions are questions which 
need further investigation. 
In these experiments in which fungi were grown in solutions of potas¬ 
sium and calcium nitrate, sucrose, and glucose it was found that in every 
case the fungi grew readily in solutions in which the diffusion tensions 
were much higher than the total diffusion tensions of the dissolved 
substances in the juices of their host plants. 
literature CITED 
(1) Berkeley, Earl op, and Hartley, E. C. J. 
1906. On the osmotic pressures of some concentrated aqueous solutions. In 
Phil. Trans. Roy. Soc. London, s. A, v. 206, p. 481-507, 3 diagr. 
(2) Carpenter, C. W. 
1915. Some potato tuber-rots caused by species of Fusarium. In Jour. Agr. 
Research, v. 5, no. 5, p. 183-210, pi. A-B (col.), 14-19. Literature 
cited, p. 208-209. 
(3) Dorn, O. 
1914. Beitrage zur Kenntnis von der Durchbohrung pflanzlicher Membranen 
durch Pilzhyphen. 48 p. Leipzig. Inaug. Diss. Abstract in Zentbl. 
Biochem. u. Biophys., Bd. 18, No. 1/2, p. 9-10. 1915. Original not 
seen. 
