130 APPENDIX A. 



sequently analogous to the blood of animals, as 

 was long since suggested by Grew ; who fur- 

 ther likened the lymphatic, or crude sap, to their 

 chyle. It is contained in delicate transparent 

 membranous tubes, which become cylindrical 

 when isolated, but when pressed together in 



bundles, assume a polygonal shape The 



movement of the latex can be witnessed only in 

 those parts which happen to be very transparent, 

 and it has not been actually seen in many plants. 

 TheFicus elastica, Ckelidonium majits, and Alls- 

 ma plant ayo, are the species upon which most of 

 the observations hitherto recorded have been 

 made. Distinct currents are observed traversing 

 the vital vessels, and passing through the lateral 

 connecting tubes or branches, into the principal 

 channels. These currents follow no one deter- 

 minate course, but are very inconstant in their 

 direction, some proceeding up, and others down, 

 some to the right, and others to the left; the 

 motion occasionally stopping suddenly, and then 

 recommencing. . . . The effect does not seem 

 to depend upon a contractile power of the tubes, 

 because the latex flows chiefly or entirely from 

 one end of a tube, even when it has an orifice 

 open at both extremities. The appearance is 

 especially analogous to the circulation of some 

 of the lowest tribes of animals, as in the Diplo- 

 zoon paradoxum, which may be divided into two 



