454 BOTANICAL GAZETTE [DECEMBER 
The author argues that the absence of high nutrition, z. ¢., germination in 
distilled water, induces the seedling to direct its energy chiefly to cell differ- 
entiation. And, vice versa, it is to be expected, and his results demonstrate, 
that a seedling grown ina rich nutrient medium, such as Knop’s solution, 
will multiply cells rapidly without differentiation. In other words, sterile 
‘soil predicates precocious sclerification ; rich soil a later appearance of the 
ultimate structure, but a more rapid division of cells without differentiation. 
Apparent counter evidence is offered by the effect of single salts, which stim- 
ulate the differentiation of particular regions, as the effect of potassium phos- 
phate on the pericycle or of magnesium sulfate on the vessels of the root. 
M. Dassonville evades a contradiction of results, asserting the latter to be a 
differentiation of a particular region called upon to play a definite réle by the 
abundance of particular substance, and holding that, for the rest, the meris- 
tem reserves as long as possible the expenditure of energy in the way of 
differentiation. The author seriously questions the taxonomic value of anatom- 
ical characters, a challenge which, with the trend wholly in the direction of 
phylogenetic characters as the ultimate basis of classification, will find few 
takers. Such specific distinctions are altogether too cumbrous for taxonomic 
purposes. 
The value of these results is apparent and we recognize the great diffi- 
culties surmounted in their attainment. The deductions, however, are by no 
means final, because there is too little accord among even the few types 
studied. Results obtained from the investigation of lupine, wheat, oats, 
morning glory, egg plant, tomato, and pine, do not permit the induction of 
general laws. Though the methods show the work to have been stupendous, 
we are impressed with the impossibility of eliminating disturbing factors aside 
from the one under consideration. For example, the author concludes that 
‘the optimum of potassium phosphate “augments only the quantity of water 
in the plant,” a result obtained from buckwheat. But, he adds, “sometimes 
the amount of dry matter is increased. It is so in hemp.’’-— JOHN GAYLORD 
COULTER. . 
