510 Cultivation of the Cacti. 



they were planted ; but, by very close inspection, the joint may 

 be discovered in all of them, by the bark being smoother, and a 

 little more shining than that on the other parts : the scar may be 

 said to become entirely obliterated in twenty years. 



This treatment causes the trees to present a more fastigiate 

 and uniform appearance, than if they had been left unpruned ; 

 the branches are also much slenderer than they otherwise would 

 have been; but when the object is to obtain straight and fine 

 timber, it may be safely adopted. 



September 10. 184' 1. 



Art. IX. Observations and Reflections on the Cultivation of the 

 Cacti. By Frederick Otto. 



(Translated from the Garten Zeitung, Jan. 2. 1841, p. 1.) 

 There has already been so much written in this periodical on 

 the cultivation of the Cacti, that it might be thought that every 

 thing relating to this group of plants was thoroughly known, and 

 the subject almost exhausted. But this is not the case; and a 

 great deal not yet made known remains to be investigated. 



In almost every garden where the Cacti are cultivated, a 

 different method is followed ; and it is always that which the 

 cultivator finds to be the most suitable and effectual in pro- 

 moting the growth and vigour of his plants. It is true that, for 

 the cultivation of this family, there is, up to the present 

 moment, no general rule which seems to be commonly received 

 every where. According to the latest accounts of the most 

 recent travellers and collectors, the Mexican mammillarias are 

 found in such a variety of situations, and in such different soils 

 (as may frequently be seen by the earth attached to the roots of 

 the original plants when they first come over), that a great deal 

 more attention should be paid to their soil than has unfor- 

 tunately been the case hitherto. Many of the species are found 

 on lime, chalk, and the fragments of stones or rocks that have 

 become broken by the action of the atmosphere ; and among 

 these may be mentioned the mammillarias discovered in Mexico 

 in 1840, and lately brought here, called M. Parkinson// Ehrenb. 

 and M. Sch lech ten dahV, both of which were found growing on 

 a chalky range of hills in Mexico, near San Onofre im Mineral 

 del Doctor; and according to the Linncea, vol. xiv. p. 375., M. 

 Humboldt// is also found on a chalky range of hills between 

 Yzmiquilpan a,nd Mestitlan. Echinocactus turbiniformis seems 

 wedded (so to speak) to bare and precipitous rocks; and the 

 Ariocarpus retusus flourishes on a moory soil, where it is always 

 moist. Were all these plants, therefore, put in a soil that the 

 gardener might fancy was congenial to them, it stands to reason 

 that they could not grow, as such a treatment would be totall}'^ 

 against their nature. If he try to excite the roots by a change 



