the Vasa propria, and Receptacles of the Juices of Plants. 271 



extent. It is this which distinguishes them from reservoirs 

 formed by lacunae of greater or less size, resulting from a com- 

 plete severance between contiguous cells. They exhibit them- 

 selves as flexuose vessels, of very unequal diameter — an appear- 

 ance due to the circumstance that the line of junction of the 

 cell-walls, which is obscure to a certain extent, resembles a spe- 

 cial wall, and that the passages {meati) follow exactly the outlines 

 of the cells between which they occur, and exhibit enlargements 

 at the angles of junction of the cells. Their granular liquid 

 occasionally intrudes into the transverse lines of junction be- 

 tween the cells ; and when this does not happen, the obscure 

 line which bounds the reservoir inflects itself between the cells, 

 and no vascular wall passing directly in face of or across the line 

 of junction can be perceived — indicating thereby that the reser- 

 voir of the elaborated fluid is not a true vessel. I have observed 

 this arrangement in several Monocotyledons — a division of plants 

 less frequently provided with milky juices than Dicotyledons, — 

 as for instance, in several Aro'idese, such as the Pathos aurita 

 and the Caladium seguinum, where utricles occur filled with gra- 

 nular fluid, and where such fluid is particularly found in inter- 

 cellular spaces. In certain cases, the mass of proper juices 

 accumulated in these meati is so dense and dark, that it cannot 

 be determined whether it is contained in a vessel or in a space 

 formed by the separation of adjoining cell-walls; in most in- 

 stances, however, it can be made out, from the indications above 

 pointed out, that it does not occupy a vascular cavity. In Cala- 

 dium seguinum the milky juice is less abundant than in Pothos 

 aurita ; and in some old leaves the section of the petioles does 

 not give issue to any white fluid ; but when young and fresh 

 leaves are selected, a pale though an undoubted milky liquid 

 escapes, which, after the preparation has been boiled, may be 

 demonstrated under the microscope to be contained within cells, 

 but particularly in the intercellular passages. 



We shall, moreover, find that, though the Colocasia odorata 

 has no distinct latex, a section of its petiole gives vent to a 

 copious discharge of mucilaginous, thick, and granular juice, 

 which is enclosed within cells as well as difl"used in a character- 

 istic manner in the intercellular spaces. This observation proves 

 beyond cavil that a great analogy subsists between the difi"erent 

 proper juices of plants, and that these fluids may disseminate 

 themselves in the intercellular passages. 



Let us now examine those lacunse, of a more or less regular 

 character, which result from the disunion of tissues. 



In Rhus typhina (Sumach) we find reservoirs of proper juices 

 which may perhaps retain in a considerable degree a vascular 

 appearance, but in reality have a structure still more widely re- 



