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Botany. — “On the influence of nutrition on the fluctuating varia- 
bility of some plants.” By Miss Tie Tammes. (Communicated 
by. Prot. Jas Morr): 
(Communicated in the meeting of October 29, 1904). 
That nutrition has an influence on the development of plants has 
long been known. Also that some parts are much more sensitive in 
this respect than others and that, for example, the size of the stem 
and leaf is much more affected by good or bad nutrition than the 
number of stamens. As yet our knowledge on this point, especially 
our quantitative knowledge, is very superficial. The introduction of 
the statistical method, however, into botany has enabled us to for- 
mulate more sharply the formerly vague and insufficiently defined 
question of the influence of nutrition and also to interpret the results 
obtained easily and accurately. 
Although the number of statistical investigations on plant charac- 
teristics, carried out in recent years, is fairly numerous, yet the 
influence of nutrition on the value of these characteristics has not 
often been studied. 
Dre Vrins') carried out an extensive investigation in this direction 
with Othonna crassifolia. He compared plants that had been grown 
in a greenhouse in pots with very dry ground with garden-cultures 
and found that with the plants from the greenhouse the median of 
the length of the leaves was only about half that of the plants that 
had grown in full ground, the average number of ray-flowers per 
head being 12 with the former, 13 with the latter. In his work 
“die Mutationstheorie’ pe Vrins*) describes experiments and obser- 
vations, the chief object of which has been the comparisón of the 
influence of nutrition with that of selection, but which at the same 
time increase our knowledge about the influence of nutritive con- 
ditions as such. He investigated the influence of these two factors 
on the length of the fruit of Oenothera Lamarckiana and Oenothera 
rubrinervis, on the number of umbel-rays of Anethum graveolens and 
Coriandrum sativum.and on the number of ray-flowers of Chrysan- 
themum segetum, Coreopsis tinctoria, Bidens grandiflora and Madia 
elegans. From his observations pr Vrims coneludes that nutrition and 
selection act in the same direction and that by stronger nutrition as 
well as by positive selection the median value of a character is 
increased. Moreover he generally observes that the variability of the 
1) Hugo pe Vries, Othonna crassifolia, Bot. Jaarb. Dodonaea, 1900, p. 20. 
2) Hueo pe Vries, Die Mutationstheorie. Bd. I, p. 368, 
