86 
Skene. — The Acidity of Sphagnum and its 
about two months a vigorous growth of Algae appeared ; in three months 
the Algae completely covered the Sphagna, so that a continued healthy 
growth of these was impossible. Haglund, as already stated, made similar 
observations, and the same thing may be seen frequently in the field with 
Sphagna growing in ditches. 
These experiments yield no data as to the nutrient value of the salts 
employed. They only show that the less acid Sphagna flourish in quite 
high concentrations of mineral solutions in artificial cultures. 
VII. Conclusions. 
In addition to the criticism and elucidation of various other points, the 
chief conclusions which may be drawn from the preceding pages are: 
1. There is a variation in acidity and in sensitiveness to chalk between 
the different species of Sphagnum. 
2 . There is a correlation between degree of acidity and degree of 
sensitiveness. 
3. The connexion between the two is indirect, not direct. 
4. The Sphagna thrive in acid solutions: the injurious effect of chalk, 
and of alkalies in general, is due to the substitution of an alkaline for an 
acid reaction. 
5. Mineral solutions are generally physiologically harmless, but may 
be ecologically harmful. 
6 . The Sphagna do actually utilize in growth bases held absorbed by 
the acid compounds of the cell-walls. 
The subject was brought to my notice by Professor Dr. Ludwig Jost, 
of Strasburg, and to him my most sincere thanks are due for this, and for 
advice and criticism. To Professor J. W. H. Trail, F.R.S., of Aberdeen, 
I am indebted for literature references, and to various friends for help, 
especially in obtaining material. 
Part of the expense was defrayed by a grant from the Carnegie Trustees, 
to whom I wish to express my obligations. 
Literature. 
1 . Baumann, A., and Gully, E. (’ 10 ): Mitteil. der kon. bayr. Moorkulturanstalt, Heft 4. 
2. Czapek, F. (’ 99 ) : Flora, vol. lxxxvi, p. 316. 
-: (’ll) : Zeitschr. f. Bot., vol. iii, p. 28. 
4 . Duggeli, M. (’ 03 ) : Vierteljahrschrift der naturf. Ges. in Zurich, vol. xlviii. 
5 . Ehrenberg, P., and Bahr, F. (T 3 ) : Journ. f. Landwirt., vol. lxi, p. 427. 
6. Engler, Arnold (’ 01 ): Ber. schweiz. bot. Ges., vol. xi, p. 23. 
