Jakuaet 14, 1810] 



SCIENCE 



59 



plant as a whole, as is evidenced by the sus- 

 pension of spore formation. This increased 

 availability of the carbohydrate food is, 

 then, distinctly unusual as far as the ordi- 

 nary life processes of the fungus are con- 

 cerned. The cessation of conidial spore 

 formation which characterizes even slight 

 stimulation is a morphological abnormality 

 in the usual life cycle of the mostly asex- 

 ual hyphomycetous fungi, and while it 

 might be argued that spore formation is 

 an evidence in itself of at least the initia- 

 tion of unfavorable conditions, such con- 

 siderations hardly apply here. It would 

 be true only in a very limited degree, for 

 the stimulus to spore formation need not 

 necessarily be inimical in any large sense 

 of the word. Whether it is the more eco- 

 nomical working of the protoplasm which 

 inhibits the formation of conidia or 

 whether the absence of the latter results in 

 less waste of energy in metabolism is per- 

 haps a question, though probably most 

 would agree that the spore-forming process 

 is one that demands a greater expenditure 

 of energy than the mere vegetative growth 

 of the hyphse. 



From what we know of the effect of 

 chemical stimulants upon the eggs of or- 

 ganisms, it would look as though the proc- 

 esses set up by such excitation are more 

 critical for the sexual cells than for those 

 of what may be regarded as the sporo- 

 phyte. It would be exceedingly valuable 

 to discover more about the relation of 

 chemical stimulation to the production of 

 gametes or their equivalents, and here we 

 have another attractive field that has not 

 been largely cultivated. It may be said in 

 passing that as far as these non-sexual 

 hyphomycetous forms are concerned there 

 is not much evidence to show that such 

 chemical stimulation as has been tried is 

 sufficient to restore the ability, in many 

 cases long lost, to produce sexual fruit. 



It has been stated that there is less wa.ste 

 as well as a greater economy In manufac- 

 ture of dry substance. One would natu- 

 rally suppose that the two go hand in 

 hand, but it is well to specify more defi- 

 nitely in what this smaller waste consists. 

 One of the characteristic products, though 

 not indeed necessarily an end product of 

 katabolic activity in the plant cell, is oxalic 

 acid, particularly in the case of these same 

 fungi which we have been considering, 

 where it is freely excreted into the sub- 

 stratum. Now the amount of this may be 

 determined with relative ease, and it has 

 been shown that with a stimulated crop 

 there is a marked decrease in the ratio of 

 the oxalic acid formed to the amount of 

 dry substance produced in a given time. 

 Together with this the carbon dioxide pro- 

 duction does not appear to much more than 

 parallel the increase in the weight; or in 

 other words, the formation of this gas is 

 approximately normal. This being the 

 case, it at once becomes evident that the 

 carbohydrate represented by the differ- 

 ence of oxalic-acid production in the nor- 

 mal and in the stimulated plants is at the 

 disposal of the organism in the construct- 

 ive processes. As for the higher plants, 

 it has been .shown that an increase in car- 

 bon-dioxide production takes place under 

 stimulation, but these results are hardly 

 complete, having been made without refer- 

 ence to net gain in .substance. This matter 

 should be further investigated, since it ap- 

 pears that the formation of wound tissue, 

 when subjected to stimulation, is accom- 

 panied on the average by a greatly less- 

 ened carbon-dioxide production as com- 

 pared with unstimulated growth; and this, 

 too, in spite of the fact that there is ocular 

 evidence that greater cell activity results 

 under conditions of stimulation. 



A highlj' interesting and instructive 

 light on this question is thrown by the be- 



