i88 3 .] 
721 
for Drosera rotundifolia. 
the feeding could be commenced. A loose piece of peat was 
cut smoothly in two, parallel to its longest surfaces, and 
boiled for half-an-hour in a culture-solution at 2 per 1000 
(50 parts potassium nitrate, 20 of calcium sulphate, 10 of 
magnesium sulphate, and 5 parts of sodium chloride). When 
cold, eighteen young plants which had just put forth their 
first leaves were set upon each of the pieces of peat in 
three rows. The peats were laid upon plates filled almost 
up to the upper edges with the same solution, fitted with 
gauze covers, and placed in a window with a south-east ex- 
posure. On June 22nd and 28th, July 1st, 6th, 12th, and 
22nd, in the beginning and the middle of August, and in the 
middle of September, all the leaves of the one series which 
showed a sufficient secretion were supplied with larger or 
smaller Aphides, corresponding to their size. Every day 
the plates were filled up with distilled water to make up for 
the loss of evaporation, and from time to time the plants 
were carefully freed from Algae. 
On July 22nd, four weeks after the commencement of 
feeding, the eighteen plants which had been fed had ninety 
leaves, and the eighteen which had not been fed ninety-five. 
The greater number of leaves of the unfed plants showed 
that those selected for this series were in the beginning the 
more advanced. But as regards the strength of the plants 
and the size of the leaves the fed plants had already the 
advantage. 
At the end of October the leaves faded. The plants were 
placed in a cold frame, looked over every fortnight, and sup- 
plied with water as it was needful. At the end of April they 
were cleaned. On May 5th, when feeding was recommenced, 
fifteen fed plants had together 126 leaves, and sixteen unfed 
plants 96 leaves. All the fed plants showed a vigorous 
growth ; of the unfed ones two only appeared equally strong. 
The remainder were partly about half as strong, or still 
feebler. Still all were apparently healthy, and their glands 
secreted in the normal manner. 
Corresponding to the increased strength of the plants and 
the larger diameter of their leaves, each leaf of the “ fed ” 
series was now supplied on the average twice weekly with a 
larger number of Aphides. The time of feeding was regu- 
lated according to the weather, selecting such as seemed 
favourable to the capture of insedts and to the secretion of 
the glands. 
During the summer blossom- heads appeared upon both 
series, and by July 26th the seed-capsules were ready to be 
gathered. The following figures will show the results ; — 
