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family are entirely destitute of leaves, the stems, which are most 

 diverse in form, performing the functions usually carried on by 

 leaves in other plants. The genus Pereskia, specimens of which 

 will be found in houses 6 and 7, have well-developed leaves ; 

 in the genus Opuntia, some species of which are known as prickly 

 pears, on the young joints of the stem will be found small awl- 

 shaped bodies — the only leaves which these plants bear — or in 

 some few species of the round-stemmed members of the genus, 

 as, for example, Opuntia teres and its relatives, leaves which are 

 quite large and remain on the stems for some time. The flat 

 bodies usually referred to as leaves in the prickly pears are not 

 such, but only flattened joints of the stem. The great diversity 

 in the form of the stem will be appreciated by inspecting the 

 entire collection in this house. In Opuntia the stems are either 

 flat or round ; in Cercus, to which belong many of the night- 

 blooming forms, they are round and ribbed in some species, 

 angled in others, erect in many, and in a large number furnished 

 with long roots, which enable them to climb on trees and rocks ; 

 in Cactus they are usually mound-shaped, pyramidal or globular, 

 and bear elongated projections in spirally arranged rows all over 

 their surfaces. The flowers of many of them are exquisite in col- 

 plant body ; or, in the case of the genus Melocactus, on a modified 

 portion at the apex. This last condition is illustrated in the col- < 

 lection by the Turk's-head cactus, Melocactus Melocactus, com- 

 mon in the West Indies. A plant of economic interest among 

 the cacti is Nopalea coccinellifera, the plant upon which the coch- 

 ineal insect breeds, several specimens of which are on the upper 

 portion of the central bench. The dye cochineal obtained from 

 these insects is the basis of the color known as carmine. An 

 odd plant is Cephalocercus senilis, from South America, com- 

 monly known as the old man cactus, for obvious reasons ; several 

 specimens of this are in the collection. Other members of this 

 family, some of them of large size, will be found in houses 6 and 7. 

 On the east bench will be found the stonecrop family, Crass- 

 ulaceae, in many genera. Prominent among these are: Coty- 

 ledon and Crassula, from southern Africa ; Echeveria, Pachyphy- 



