80 LACTIFEROUS TISSUE. 



the pith, in the bark of the roots, in connection with the 

 spiral vessels, and it is said, in the cells of hairs. We have 

 readily detected this tissue in the liber of a vigorous fig, in 

 which the vessels were distended with fluid. We failed in 

 many attempts, in distinguishing the cinenchyma, until we 

 adopted the following course : by applying a ligature to a 

 branch of fig so tight as to prevent circulation, we then cut 

 the branch below the ligature, and with care, removed half of 

 the bark and all the wood of an internode, and by carefully 

 reducing a portion of the bark to a sufficient thinness, and 

 removing the exuded sap, we brought the thin portion under 

 the microscope, and saw, in the most distinct manner, the 

 tubes distended with fluid, and the vigorous circulation made 

 visible by the numerous globules floating in the enclosed fluid. 

 This circulation is denominated Cyclosis, of which we shall 

 speak hereafter. This tissue is called the Lactiferous, from 

 the circumstance of its containing the milky juices of plants. 

 When the Fig, Lettuce, Asclepias, and Euphorbia are wound- 

 ed, a milky juice immediately issues ; this proceeds from the 

 severed vessels ot the cinenchyma. Although in these cases 

 the latex (the name of the fluid contained in this system of 

 vessels) is white, in others it is colorless, and in some yellow. 

 It is the most highly elaborated juice of the plant, and the sap 

 seems, in this system of vessels, to be prepared for the nour- 

 ishment of the plant. 



.34. We have given above the forms of tissue which go to 

 make up every vegetable, from the humblest plant to the lar- 

 gest tree of the forest. However various their forms and ap- 

 pearances, they are all composed of one or more of the above 

 varieties. It becomes a subject of prime interest to the inqui- 

 ring Botanist, to trace the origin of these several tissues. — 

 Much labor has been bestowed on this subject, and much dis- 

 cussion has been occasioned by the different views of differ- 

 ent individuals. There are two prevailing opinions on the 

 subject. Some believe that there are several primitive forms of 

 tissue, formed directly from the vegetable membrane as before 

 described. Others are of the opinion that cells only are form- 

 ed from this membrane, and that all the other tissues are varia- 

 tions of the cellular. We have already expressed our belief 

 that the woody fibre is a modification of the cellular tissue. 

 We are equally convinced that the spiral vessels and ci- 

 nenchyma have the same origin. The following are some of 

 the considerations which have led us to this conclusion. — 

 First, in the earliest stage of the embryo, nothing but cells 

 are to be discovered, by the most powerful instruments. Se- 



