214 DROSERA ROTUNDIFOLIA. [Cuap. XL 
cloudy; and this has been observed within 10 s. after a 
gland has been excited. Granules just resolvable under a 
very high power soon appear, sometimes within a minute, in 
the cells beneath the glands; and these then aggregate into 
minute spheres. The process afterwards travels down the 
tentacles, being arrested for a short time at each transverse 
partition. The small spheres coalesce into larger spheres, or 
into oval, club-headed, thread- or necklace-like, or otherwise 
shaped masses of protoplasm, which, suspended in almost 
colourless fluid, exhibit incessant spontaneous changes of 
form. These frequently coalesce and again separate. If a 
gland has been powerfully excited, all the cells down to the 
base of the tentacle are affected. In cells, especially if filled 
with dark red fluid, the first step in the process often is the 
formation of a dark red, bag-like mass of protoplasm which 
afterwards divides and undergoes the usual repeated changes 
of form. Before any aggregation has been excited, a sheet 
of colourless protoplasm, including granules (the primordial 
utricle of Mohl), flows round the walls of the cells; and this 
becomes more distinct after the contents have been partially 
aggregated into spheres or bag-like masses. But after a 
time the granules are drawn towards the central masses and 
unite with them; and then the circulating sheet can no 
longer be distinguished, but there is still a current of trans- 
parent fluid within the cells. 
Aggregation is excited by almost al! the stimulants which 
induce movement; such as the glands being touched two or 
three times, the pressure of minute inorganic particles, the 
absorption of various fluids, even long immersion in distilled 
water, exosmose, and heat. Of the many stimulants tried, 
carbonate of ammonia is the most energetic and acts the 
quickest; a dose of 37:55 of a grain (00048 mg.) given to 
a single gland suffices to cause in one hour well-marked 
aggregation in the upper cells of the tentacle. The process 
goes on only as long as the protoplasm is in a living, vigorous, 
and oxygenated condition. 
The result is in all respects exactly the same, whether a 
gland has been excited directly, or has received an influence 
from other and distant glands. But there is one important 
difference; when the central glands are irritated, they 
transmit centrifugally an influence up the pedicels of the 
exterior tentacles to their glands; but the actual process of 
aggregation travels centripetally, from the glands of the 
