1900] CURRENT LITERATURE 69 
criteria when an interpretation totally at variance from that upon which his 
conclusions depend is at least admissible. Thus at the very outset he devotes 
a number of pages to the discussion of ‘criteria for the relative water- 
demand of plants.” He seeks a ready means of determining in extended 
observations whether or not mycorhiza when present is associated with 
reduced transpiration, as his hypothesis demands. The presence of starch 
rather than sugar in the leaves is selected as the foremost characteristic for 
his purposes indicative of greater transpiratory activity. ‘For,’ he writes, 
“the advantage of starch formation lies very largely in the promotion thereby 
of transpiration, since reduced concentration stimulates the evaporation 
rate ; and, inversely, an increase of the dissolved substances, glucose, for 
example, must have a retarding effect.’’ But it is a fair question whether 
starch may not appear only after a maximum concentration has been attained, 
and hence its absence regarded as favorable rather than opposed to trans- 
piration, 
Certain experiments upon Sinafis alba, Linum usitatissimum, and 
Triticum vulgare, forms free of any trace of mycorhiza, are of interest in 
affording striking contrast with Frank’s experiments upon beech and pine 
seedlings. Inthe latter case, as is well known, the development in a sterilized 
soil of seedlings normally possessed of mycorhiza was strikingly deficient in 
contrast with individual plants in unaltered humus soil. But, if the conten- 
tion of Stahl is sustained, autotrophic forms should flourish in especial degree 
in soil where they are freed of the rivalry of fungi, which unlike their more 
specialized mycotrophic kin, they are unable to make tributary; z¢., exactly 
the reverse of the results with mycotrophic forms. And such is found to be 
the case in striking degree. Incidentally, however, an excursion is made to 
demonstrate the retarding effect of abundance of nutrient salts upon root 
Stowth. For, though the shoot is feeble, the root system, as is reasonable to 
expect, becomes more elongated in the autotrophic forms grown in competi- 
tion with the fungi. 
That part of the paper which deals with “the absorption of nutrient 
salts and the ash-content of mycotrophic as compared with autotrophic 
Plants” is none the less important in that it seems to belong as a closing 
Ps Pter to such special studies of this subject as those of MacDougal and 
isa than to a contribution so broadly comparative in character as 
alge be Ee rence argument that the ash content of mycotrophic 
ti aoe = ah certain specific differences from that of autotrophic Roi 
teas he mated upon the previous and detailed study of others, tts 
is pee is Nese of mycorhiza with forms limited in their possi at 
ice pen a food-elaboration, however broad and striking that associa- 
Patalletignn mE uffice it for the argument that his examples show a certain 
bana aad 4. exist between a greater ash-content and autotrophy on the one 
Ss ash-content and mycotrophy on the other. This tends to 
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