386 PINGUICULA VULGARIS. Caar. XVL 
and Bromus. Most of these seeds did not excite any secretion 
until 48 hrs. had elapsed, and in the case of the Trifolium only 
one seed acted, and this not until the third day. Although the 
seeds of the Plantago excited very little secretion, the glands 
continued to secrete for six days. Lastly, the five following 
kinds excited no secretion, though left on the leaves for two 
or three days, namely lettuce, Hrica tetralia, Atriplex hortensis, 
Phaluris canariensis,and wheat. Nevertheless, when the seeds 
of the lettuce, wheat, and Atriplex were split open and applied 
to leaves, secretion was excited in considerable quantity in 
10 hrs., and I believe that some was excited in six hours. In 
the case of the Atriplex the secretion ran down to, the margin, 
and after 24 hrs. I speak of it in my notes “as immense in 
quantity and acid.” The split seeds also of the Trifolium and 
celery acted powerfully and quickly, though the whole seeds 
caused, as we have seen, very little secretion, and only after a 
long interval of time. A slice of the common pea, which how- 
ever was not tried -whole, caused secretion in 2 hrs. From 
these facts we may conclude that the great difference in the 
degree and rate at which various kinds of seeds excite secre- 
tion, is chiefly or wholly due to the different permeability 
of their coats. 
Some thin slices of the common pea, which had been pre- 
viously soaked for 1 hr. in water, were placed on a leaf, and 
quickly excited much acid secretion. After 24 hrs. these slices 
were compared under a high power with others left in water 
for the same time; the latter contained so many fine granules 
of legumin that the slide was rendered muddy; whereas the 
slices which had been subjected to the secretion were much 
cleaner and more transparent, the granules of legumin appa- 
rently having been dissolved. A cabbage seed which had lain 
for two days on a leaf and had excited much acid secretion, 
was cut into slices, and these were compared with those of 
a seed which had been left for the same time in water. Those 
subjected to the secretion were of a paler colour; their coats 
presenting the greatest differences, for they were of a pale dirty 
tint instead of chestnut-brown. The glands on which the 
cabbage seeds had rested, as well as those bathed by the sur- 
rounding secretion, differed greatly in appearance from the other 
glands on the same leaf, for they all contained brownish granular 
matter, proving that they had absorbed matter from the seeds. 
That the secretion acts on the seeds was also shown by some 
of them being killed, or by the seedlings being injured. Fourteen 
cabbage seeds were left for three days on leaves and excited 
