116 On the Genus Ficus. 



important of the Indian species, in an economic point of view, 

 is F. elastica, Boxb. It is a tree growing some thirty or forty- 

 feet high, with large oval or oblong leaves, very thick and 

 glossy, and is now well known as a common conservatory and 

 parlour plant. The fruits are arranged in axillary pairs, sessile, 

 or without stalks, not larger than an olive. From this species- 

 most, if not all, the caoutchouc or India rubber brought from 

 the East Indies is obtained. We all know how abundantly a 

 white milk flows from the least fracture occasioned to any part 

 of this plant, the prick of a pin upon its stem or thick green 

 leaf will cause it to ooze out, and by exposure to the air be- 

 come thick and elastic. When collected in its native country 

 for commercial purposes, deep incisions are cut through the 

 bark nearly down to the wood, in a transverse direction, and 

 about a foot apart. The juice flows from these wounds in large 

 quantities, and, on coming in contact with the air, forms itself 

 spontaneously into a solid elastic substance, from which a kind 

 of whey or foetid fluid separates. After such a tapping as this, 

 the tree is said to require but a fortnight's rest before it is 

 ready for a similar operation. The presence of caoutchouc or 

 milky juices in plants is a character of many natural orders. 

 Some yield a pure milky fluid, which never hardens. The 

 vessels that contain this fluid are called laticiferous tissue, or 

 cinenchyma. They are very minute, the average diameter of 

 one of them not exceeding 1 4 ' 00 of an inch. One of the 

 chief distinctions of these vessels is, that they lie in no 

 regular or definite position to the other tissue, and consist 

 of long branching tubes, as seen at Fig. 3. In their young 

 state, they are very thin and hair-like, but as they get older, 

 they become large, their sides thicken, and contract in some 

 places, and swell in others. This has given rise to an 

 opinion amongst some botanists that they are merely a series 

 of cells, placed end to end, in which the partitions have become 

 absorbed, as there are no divisions through their entire length. 

 The contents of these tubes, called the latex, is not in all plants 

 milky, but sometimes coloured, and at other times quite trans- 

 parent and colourless. It is always of a granular nature, but 

 its chemical composition varies in different plants ; for while 

 some give a perfectly harmless, and even a nutritious milk, 

 others are acrid and narcotic. The cells which contain caout- 

 chouc, and similar juices, must therefore not be confounded 

 with the cells or vessels through which the ordinary nutritive 

 functions of the plant are carried on, nor must the fluid itself 

 be confounded with the sap. 



The common Fig (Ficus carica, L.) is perhaps the best 

 known of all the species, owing to its valuable fruit. As we 

 have before said, its native country is doubted. The plant is, 



