408 M. Lestiboudois on the laticiferous Vessels of Plants. 



In other plants where the juices are more coloured and denser 

 in their lower portions, they are there less abundant : thus, for 

 example, in Chelidonium, sections of the root are followed by a 

 very small discharge of laticiferous fluid. The Asclepias sj/riaca, 

 which possesses so many latex-vessels in its stem, has very few 

 such in its stock, and none at all in those parts which give off 

 no buds : for instance, the portions contiguous to the aerial 

 stems allow the escape of a coloured fluid ; while the remoter 

 parts, together with the roots, give off a scarcely appreciable 

 quantity. I should state, however, that I have sometimes ob- 

 served a few isolated vessels in the roots. These radical vessels 

 are impregnated with a mucilaginous liquid, of thick consistence 

 ■ and capable of coalescing in little globules of various diameters, 

 themselves sometimes becoming confluent, and apparently being 

 proper j uices. 



In certain plants the coloured fluids, instead of being less 

 abundant in the roots, accumulate there in a larger quantity 

 than in the aerial portions : thus, in the stem of Lactuca sativa 

 the vasa propria do not constitute the principal elements of the 

 cortical bundles, which are composed of woody fibres ; whilst in 

 the root they almost exclusively form the cortical bundles, into 

 the composition of which few fibres enter. Hence this portion 

 of the plant contains the largest proportion of the laticiferous 

 juices; and on tearing the plant up by the roots, little drops of 

 white fluid are seen to escape from all the torn ends of the 

 fibrils. 



As a rule, the vasa propria are distinguishable from neigh- 

 bouring tissues, and particularly from cortical fibres, by the cir- 

 cumstance of their being filled with a granular fluid of some 

 particular colour, and by their flexuous, thin, branching, ana- 

 stomotic, and isolated form — the fibres being, on the contrary, 

 straight, parallel, closely packed, and often empty. However, 

 in certain plants these proper vessels are straight, very long, 

 with few ramifications, and contain excessively minute granules 

 few in number ; on the other hand, cortical fibres occur of very 

 fine calibre, of delicate form, and more or less filled with granular 

 matter, and therefore not so readily distinguishable from vasa 

 propria. This happens in Campanula Medium, C. rapuncu- 

 lo'ides, and C.pyramidalis, in Euphorbia Lathyris, E. sylvatica, &c. 

 The distinction is rendered still more difficult when the vessels 

 are articulated. According to Schultz, the articulations are not 

 primary, but are the consequence of age ; on this point we shall 

 have something to say hereafter. The reported movements of 

 expansion and contraction we shall also defer, remarking here 

 only that though the difficulties in determining the existence 

 of proper vessels are often great, yet the plan of boiling the 



