PLANTS FOR WINDOW GARDENING. Ill 



dinary fact, which puzzled the botanists, a beautiful blue. 

 It had been asserted and argued, with great show of reason, 

 that a flower, of which all the known varieties, or the gen- 

 eral types, were of red, yellow, or cognate colors, could, by 

 no possibility, be found related to a plant with blue flowers, 

 or could there be a blue flowering plant in the same class. 

 The discovery of a blue tropaeolum, in 1844, completely 

 refuted this theory. In the treatment of the tropaeolum, it 

 is essential for the good health of the plants that they 

 should enjoy plenty of light and air ; without this, they can- 

 not fail to become sickly or unsightly from faded leaves and 

 small flowers. A supply of water should be given with the 

 syringe, overhead, occasionally, which will conduce to the 

 vigor of the plant, and destroy the red spider, which some- 

 times attacks the leaves. The plant, in all its varieties, is 

 remarkably free from disease or insects ; we have occasion- 

 ally had the more delicate varieties troubled by green fly, 

 and by mealy bug, but very little care will prevent this. 

 The chief danger seems to lie in the decaying of the roots 

 by over-watering when in growth, or by not withholding 

 water when they are in a state of rest. These remarks, of 

 course, apply only to the bulbous varieties. Sometimes we 

 have known the roots of the summer-blooming varieties to 



