278 BULLETIN OF THE BUSSEY INSTITUTION. 
and plants abound in fertile soils, but that the fertility is to be ascribed 
in part to their presence. According to Cohn (/oc. eit., p. 219), 
diatoms abound not only in most natural waters, both fresh and putrid, 
but in every moist Soil, whether it be that of swamps or the edges of 
ditches, of gardens, or of flower-pots. ‘The dry loam of ordinary fields, - 
though far less highly charged with microscopic forms of life, is by no 
means free from them. be 
The history of the derivation of the very name “ infusoria ” enforces 
the lesson that animalcules must be abundant wherever moist vegetable 
remains are in process of decomposition. According to Stein,* the 
term “ Jnfusionsthier” was first used in 1763 by Ledermiiller, because 
of the facility with which in winter weather he could procure living 
microscopic objects on allowing an infusion of hay in water to stand 
two or three days in a warm room. As Stein remarks, hay is spe- 
cially well suited for the purpose in question, since it usually comes 
~ from meadows where the infusoria abound. 
In this view of the matter, it is interesting to note the facts that it 
is in well-moistened soils such as the diatoms love to inhabit that 
plants are observed to avail themselves most readily of the soil-nitrogen, 
and that certain crops which can be grown without the help of nitro- 
genous manures, such as clover, beans, turnips, and other large-leaved 
plants, are precisely those which shade the soil and serve, like the pro- 
cess called mulching, to keep its surface moist. In the course of the 
experiments whose results have been recorded above on pages 254-261, 
I have repeatedly had occasion to notice the favorable influence that is 
exerted by an abundant supply of moisture upon the utilization of the 
soil-nitrogen by plants. ‘The appearance of the plants thus thoroughly 
watered was comparable with that of plants growing in the moist soil of 
a closed glass case (Ward’s case) ; and it may be noted in this connection 
that Boussingault f had no trouble in growing a good crop of cresses and 
of various weeds at the expense of the soil-nitrogen in an apparatus of 
that kind. The importance of moisture, as thus exhibited, recalls the 
results of practical field experience as to the use of oil-cake and certain 
other of the organic nitrogenous manures. Thus, even in a climate 
845, and 2. 840; that of Lawes, Gilbert, & Pugh, Philosophical Transactions, 
151, 582; and that cited by Mulder, “ Chemie der Ackerkrume, 2. 103. 
* Stoeeckhardt’s ‘‘ Chemische Ackersmann,” 18638, 9. pp. 211, 212. 
Tt “ Agronomie,” 1. 67. 
