MICROSCOPIC LIFE OF THE "LEAF-CARPET." 245
by the microscopic fauna and flora both collectively and indi-
vidually in the peculiar environment of the leaf-carpet. Generally
speaking, all the organisms are engaged in some way in the
disintegration and transformation of the dead leaves into humus.
But this is undoubtedly a very complicated process and it would
be most interesting to know how each contributes to this end.
Investigations by workers on the organisms of soils in general
have no doubt given an idea of some of the relationships that
exist between some organisms to one another and to their
environment, but the problem of such relationships as a whole,
including those within the leaf-carpet, still awaits solution.
REFERENCES
1. Bornebusch, C. H. (1930). The Fauna of Forest Soil. Det
Forstlige Forsogsvaesen I Danmark. Bd. XI, Hefte 1. (In
English with Danish summary. A very interesting work, but
not dealing with the micro-organisms except mites and
Collembola.)
2. France, R. H. (1921). Das Edaphon. 2nd Ed. Stuttgart.
3. Jones, P. M. (1937). Soil Amoeba (Naegleria Gruberi) coalesce
to form a plasmodium. American Naturalist, 71, pp. 488-499.
4. Muller, P. E. (1887). Studien uber die naturlichen Humusformen.
Berlin.
5. Niethammer, A. (1937). Die mikroskopischen Boden-Pilze. The
Hague.
6. Ramann, E. (1911). Bodenkunde. 3rd Ed. Berlin.
7. Russell, E. J. (1937). Soil Conditions and Plant Growth. 7th
Ed.
8. Sandon, H. (1924). Some Protozoa from the Soils and Mosses
from Spitzbergen. Journ. Linn. Soc. Zool., xxxv, pp. 449—495.
9. Sandon, H. (1927). Composition and Distribution of the Protozoan
Fauna of the Soil.
10. Sigmond, A. A. J. de. (1938). The Principles of Soil Science.
11. Varga, L. (1935). Daten zur Kenntnis der Protozoenfauna des
Waldbodens von Eberswalde, and Die Protozoen und ihre
Verteilung im Waldboden von Tharandt. Zentralblatt f.
Bakteriologie, &c. Bd. 93, pp. 32-38 & 128-137.
12. Waksman, S. A. (1932). Principles of Soil Microbiology. 2nd Ed.
13. Waksman, S. A. (1938). Humus. 2nd Ed.
EXPLANATION OF THE PLATE.
1. Cryptodifflugia oviformis, Penard (=? Geococcus vulgaris,
France). Specimen with
pseudopodia extended, also
showing nucleus and two con-
tractile vesicles. X 1500.