AUTUMN NUMBER 29 
white sand and some small cabbage plants, whose roots had been 
washed clean of all earth, were placed in them. The object was 
to remove all plant food, as far as possible, and give the plants 
nothing but what was in the solutions added. The plants were 
placed under lantern globes in the laboratory and divided into 
four groups of two plants each. One lot was watered with a 
1% solution, one with a 5% solution and one with a 10% solution 
of magnesium sulphate, and the other with distilled water for a 
check. The sand was kept moist by watering every day and the 
results recorded daily. The 5% and 10% solutions were found 
to be too strong and the plants soon died. Some winged forms 
were found on all but two of the plants however. 
The experiment was then repeated, this time using three per 
cent solutions which would not affect the plants so quickly. 
Hight cabbage plants were cleaned and potted as before and 
divided into four groups. One group was watered with a 3% 
solution of each of the following: magnesium sulphate, sodium 
chloride, tannic acid, and one group with distilled water for a 
check. In no ease did the plants live more than a few days. They 
soon began to turn yellow, probably from lack of food, and con- 
sequently the aphids left them and started wandering around 
and died. As the table shows, wings were produced in some of 
them, but without much consistency. Although the checks pro- 
duced no winged forms, one plant in each of the other groups 
showed none also. The experiment did not run over a long 
enough period to be conclusive. There was not sufficient time 
for the aphids to mature and show the effects of the chemicals. 
Besides we cannot prove that the plants took up any of the 
chemical solutions added, since the roots have the power of dis- 
criminating between the available foods. Therefore some at- 
tempts were made to rear them on cut stems in chemical solu- 
tions. 
Experiments with Cut Stems. Eight young orange tips were 
cut from a tree and placed in small pots of clean white sand 
which were covered with lantern globes and set in the green- 
house on a shaded bench. On each of these cuttings were placed 
a number of aphids of the species Aphis gossypii. Two of them 
were watered with a 3% solution of each of the following chemi- 
cals: magnesium sulphate, sodium chloride and citric acid; and 
two were watered with distilled water for checks. The results 
were recorded as long as the cuttings kept fresh and the aphids 
