Dec., 1908 .] 
The Effect of Alkaloids. 
411 
From this table it will be observed that strychnine, especially 
in the stronger concentration acted poisonously upon the plants, 
checking rather than stimulating their regenerative power. 
Even a superficial examination of the Tables I and III will leave 
no room for doubt as to the very large difference between the 
first and the second regeneration in favor of the former. And in 
spite of the fact that after the second operation the plants had 
been regenerating for a longer period of time, the regenerated 
Fig. 5. Diagram of decapitated plants; a —old epicotyl, 
b and c —regenerating stems. 
"■ I’ 
stems wer£ by far smaller than those regenerated after the first 
operation. That the difference is not to be attributed to an 
exhaustion of food materials was evident because the cotyledons 
were still of a, large size. Furthermore, McCallum (4) demon¬ 
strated in a, sejiles of ingenius experiments that food is not a 
necessary factor in. regeneration of Phaseolus, and that the 
plants regenerate even with the cotyledons removed. 
CONCLUSION. 
In summing up the facts presented in this note it may not be 
amiss, perhaps, to discuss briefly their relation to facts obtained 
in other similar studies. It was shown in the foregoing that 
alkaloids, such as pilocarpine, atropine, strychnine and digitalin 
exert a stimulating influence upon regenerating plants, increasing 
the rate of regeneration. Yasuda (7) found from his study of 
the effect of alkaloids upon moulds that “the moulds generally 
grow' better in the solutions which contain alkaloids than in the 
normal control-solution.” (p. 82.) He also found that strychnine 
produced no poisonous action on the moulds until the limit of 
saturation w r as reached (about 2.5%). Plants behave somewdiat 
differently in this respect from animals. In a recent w r ork on the 
effect of alkaloids upon the early development of eggs of the sea- 
urchin, Toxopnenstes variegatus, conducted at the Bermuda 
Biological Station (5c), atropine, strychnine and digitalin were 
found to inhibit the developmental process, the last two sub¬ 
stances being so much toxic that normal development was pos¬ 
sible only in very dilute solutions. Neither did pilocarpine 
stimulate or accelerate to any marked degree the development of 
the eggs of this sea-urchin, although the literature contains a 
