PHYSIOLOGICAL STIMULI AND ITS SIGNIFICANCE 25% 
feuilles; ils levent alors leurs Oignons, en choisissant un beau jour qui 
est plus nécessaire pour cette opération que pour planter; (bl. 95). | Il 
y a des années où l’air de Juin, qui est la saison ordinaire de cette opé- 
ration, est ford chaud.” (bl. 97). 
Like VOORHELM, ST. SIMON distinguishes between breeders who regu- 
late their work more in connexion with the time, than in reference to 
the degree of maturity of the bulbs and such who do not work so me- 
chanically. In his book he says: 
„Lorsque les fannes commencent a se dessécher, les Fleuristes arra- 
chent les oignons de terre, avec la main, autant qu'il est possible, de 
peur que la bêche n’offense les oignons ou les cayeux. Ils coupent alors 
les fannes totalement, remettent l'oignon en terre sur le coté, le recou- 
vrant de deux ou trois doigts de cette terre quiest très-légère comme on 
l’a vu. On laisse les oignons un mois ou environ dans cet état.”” (p. 149). 
„Tous les Fleuristes suivent ce procédé, mais ceux qui ne se bornent 
point au simple mécanisme du métier, savent les distinctions qui con- 
viennent à chaque espèce, pour les faire jouir de tous les avantages que 
l’art peut leur procurer” etc. (p. 149—150). „On transporte les oignons 
dans les Serres vers la fin de Juin ou environ” (p. 150). 
How in 1794 „a group of scientists’ judged about the advisability 
to allow the bulbs to reach their natural maturity, may be shown by 
the following citation (translated from the Dutch) in „Nederlandsch 
Bloemwerk”: „The excellency of the hyacinths, certainly deserves, in 
our opinion, that one takes the trouble not only to prepare a good soil 
for them, but also to take all possible care of them, to prevent their 
being hurt by untoward circumstances or their being weakened by a 
useless spilling of force; the latter we prevent especially, by cutting the 
leaves an inch or an inch of a half above the soil (of those plants 
namely of which no seed shall be harvested) before the time of flowering 
is over, because the useless feeding of all those leaves, until they are, so to 
speak, removed by Nature itself, is a great loss of force; it might even 
be considered, whether it would not be advisable to cover the wounds, 
caused by the cutting, by a plaster of graft-wax, to keep the fluids wi- 
thin the bulb, to concentrate them and so to strengthen them; this 
however we only ofter as a suggestion.” 
The impedement of photosynthesis by a cutting off of the leaves 
followed by leaving the bulbs in the soil, during a certain period, has, as 
I could show this year, a similar effect as the harvesting of them while 
Genetica V 17 
