CACTACEOUS PLANTS. 



77 



both pot and roots of any having white matter in the earth or 

 round the inside of the pot. The eggs of these insects being 

 microscopic, I even think it best to put the pots on the kitchen 

 stove and give them a good baking before again using them. 



The pests of scale and thrip are not so troublesome, as they 

 mostly seem to infest plants that you can easily remove them 

 from by means of a piece of pointed wood. I have found it a 

 good plan to give all such affected plants a change of situation 

 after cleaning them, if only to a light sitting-room, the insect 

 not then reappearing. Scale is said to come from an insect 

 depositing its eggs upon plants that may be too damp, and is 

 like a small oyster, spotting the plant, the insect inside it eating 

 into the plant. Thrip is a smaller insect, appearing generally in 

 clusters, of a light brown colour, and of a long form. They are 

 easily removed, and are most often (with scale) found on Opuntias. 



Rain-water is best for these plants, as when using it daily in 

 the summer the chalk in spring- water is deposited on the plant, 

 leaving unpleasant spots. When the warmer weather of March 

 and April arrives it is usual to let out the fire of the heating 

 apparatus, many persons not lighting their fires again until the 

 external thermometer gets down to 40° F., but it is better to 

 keep the fire going all the winter, as the house can be so much 

 better ventilated. Great help is also given to the plants when 

 they are growing in May, and even in June, by lighting the fire 

 on the cold days and nights that often come in these months, as 

 the growth is not then checked. Some persons like in the 

 spring to water the plants with a little admixture of ammonia. 

 I have never tried the effect, but think it a sure method for 

 killing any insects in the soil, if it did nothing else. 



It is difficult to condense in the short space of a lecture all 

 that may be said on this subject ; but if one wishes to study the 

 wonderful works of nature, and to learn the mysterious dispen- 

 sations of Providence in allotting to each country the plants 

 most suitable to it, he cannot do better than cultivate Cacti, for 

 in any given conservatory you can grow double or treble the 

 number of plants of this kind than of any other sort, as they 

 take up so much less space, whilst their flowers are most 

 gorgeous and beautiful ; but whether in bloom or not, their 

 very forms are most pleasing, and a man cannot help 

 being wiser in studying them, and his mind must be in 



