On the Mafiagement of Cacti. 169 



Art. IX. On the Management of Cacti. By N. M. T. 

 In managing cactoid plants, particularly the Cereus tribe, it is 

 customary to give them, while blooming, a more liberal supply of 

 water than at other times, but experience has convinced me that 

 this is sometimes injurious in some species. In the spring of 

 1838, a plant of the Cereus hexagonus under my care showed 

 flower buds ; when I applied a little more moisture, and had the 

 mortification to see the buds turn black, and drop when about 

 the size of peas. In the autumn of the same year it again 

 produced flower buds, and the same treatment had again the 

 same effect. This determined me to pursue a different method ; 

 and, as soon as it showed flower in 1839, I withheld water en- 

 tirely ; the buds continued to swell rapidly, and the whole 

 number (five) expanded beautifully; and, in 1840, no less than 

 fourteen of its fine large ephemeral flowers arrived at the greatest 

 perfection. 



This plant is, I believe, generally deemed a shy bloomer, and 

 from the liability of the buds to drop when very small (if 

 water is supplied), it is probable its flower buds are often im- 

 perceptibly sacrificed, and a knowledge of these facts may lead 

 to greater vigilance. Much has been attributed to the influence 

 of light in causing these plants to flower; but the plant men- 

 tioned would indicate that a certain age, or maturity of organi- 

 sation, is the only requisite (plenty of light may sooner produce 

 the latter certainly), as its great height causes it to be placed in 

 the back of a vinery, where it is densely shaded during the 

 blooming season. 



When a hypothesis appears that seems reasonable, and has 

 passed current for a time, we are too apt to adopt it without 

 questioning its validity, or bringing proof to its support. So it 

 is with some of the effects attributed to light ; for instance, plants 

 taken from the protection of glass, and exposed to the open air, 

 are said to become discoloured from its direct influence, but this 

 is not the case. Take a plant from a warmer to a colder climate, 

 from a stove to a greenhouse, where the light is equally indirect, 

 equally qualified, and the same effect is produced as if taken 

 from the shelter of glass to the open air ; demonstrating that it 

 is produced by change of temperature only. Of this, last 

 spring afforded me convincing proof. During March I turned 

 out several things, and planted them in a sheltered corner (in 

 the manner described in a paper at the time), to enable them to 

 get rid of this discolouration previously to their being planted out 

 in beds fully exposed to the sun. In April, which was intensely 

 hot, they soon assumed the unspotted hue of perfect health, 

 while the cold, cloudy, unseasonable weather that suddenly fol- 

 lowed, in a few days turned them as " brown as berries." Light 

 has no hand whatever in producing this appearance. Cold pro- 



