118 
IOWA ACADEMY OP SCIENCE 
Geo. F. Atkinson^ in the bulletin, “The influence of mushrooms on the 
growth of some plants,” gives a valuable contribution to the question of the 
ability of plants to use soluble organic matter directly as food. The author 
first proves that mushrooms are available for food for several green plants, 
both when fermented and when unfermented. These were not tested under 
sterile conditiqns and the unfermented had a chance to ferment, and therefore 
it is not certain that the organic compounds were used unchanged. 
He next grew radish and cabbage in pure cultures with agar as a substratum, 
and he found that both the fermented and the unfermented mushroom material 
caused some growth of the plants, although not quite so much as that caused 
by the nutrient solution. We quote: “These pure cultures show that for the 
radish and cabbage there is plant food for autotrophs in an unfermented in- 
fusion of the common mushrooms, for they grew to a larger size here than in 
distilled water. The unfermented mushroom, however, does not offer so good 
a nutrient as the products of fermentation do, and this is not surprising, 
although it is a little surprising that the unfermented mushroom can serve 
as a nutrient for autotropic green plants. Mendel has shown, however, that 
a considerable part of the nitrogen in mushrooms probably exists as non-proteid 
nitrogen, some in the form of cellulose nitrogen and some in a form that can 
be extracted with alcohol. The former probably becomes available in the fer- 
mented mushroom, while the latter is directly available in the infusion of the 
unfermented mushrooms.” The author thinks the evidence conclusive that the 
plants used the nitrogen directly as it was found in the mushrooms without 
its being changed into the nitrate or ammonia form. This is undoubtedly true 
if it is certain that the only way organic compounds of nitrogen can be con- 
verted into the ammonia or nitrate form is through the action of bacteria. 
This point has been considered settled by bacteriologists. The only other ex- 
planation is that the organic substances were changed by the direct oxidizing 
action of 'the roots of the plants themselves. There is very little evidence to 
support this view, however, and it seems probable that in this case soluble 
organic matter was used directly as plant food. 
One more reference will be given. It is to the article of J. Lefevre^ entitled, 
“The development of chlorophyllous plants in the absence of carbon dioxid, 
but with non-toxic quantities of amids.” A series of experiments were con- 
ducted with cress and sweet basil grown in pots under bell jars without carbon 
dioxid, but in the presence of a number of amids. The plants were supplied 
with chemical fertilizers to which was added a mixture of tyrosin, oxamid, 
glycocoll, alanin, and leucin at the rate of 1.1 g. for every 500 g. of soil. The 
plants were observed under conditions of light and darkness, and it was found 
that in the presence of sunlight they were able to make considerable growth, 
attaining in six weeks a size fully ten times that of the original, and with well 
developed foliage and flower buds. As this growth took place in the entire 
absence of carbon dioxid, the carbon required must have come from the amids 
and was taken up by the roots. That the transfer was not simply osmotic, but 
true synthesis, is shown by the absence of all, or nearly all, growth when the 
plants were kept in the dark. Apparently photosynthesis took place in almost 
normal amount. 
But if it is admitted that plants can, under certin conditions, use organic 
substances directly as food, it has not been shown how general the practice is. 
^Cornell, N. Y., Exp. Sta. Bull. 240. 
^Bxp. Sta. Rec. 19, p. 22. 
