FUNCTION.] WHICH HOWEVER DOES NOT EXIST. 341 



when viewed by transmitted light. In the larger vessels (vasa 

 expansa) the latex appears stationary; but in the smaller 

 ramifications it is seen to move rapidly or slowly, by starts or 

 in a steady current, carrying along with it single globules or 

 several together, which are forced along the passage in the 

 vessels, much as pieces of wood might be expected to be 

 carried in water through a narrow and sinuous channel. It 

 looks as if the matter of the latex met with frequent obstruc- 

 tions, which stopped the current for a moment and then gave 

 way, when a rapid flow goes on till it is again interrupted. 

 Professor Morren has also mentioned the young flowers and 

 receptacle of the common Fig, as an extremely easy subject 

 in which to find the motion. 



If, however, the fine capillary ramifications of the cinen- 

 chyma upon the surface of plants will satisfy the enquirer, 

 the movement of cyclosis may be readily found in almost any 

 lymphatic hair, provided the microscope employed will 

 magnify 350 diameters. Tradescantia virginica is usually 

 employed for this purpose, but in reality any hair will show 

 it, especially if the latex be milky. It is then seen, to use 

 the words of my lamented pupil, Mr. Slack, that each joint 

 of the hair consists of an outer glassy colourless case, enclos- 

 ing the colouring matter. A nucleus (cytoblast) is situated 

 at the base of the joint, and currents of small particles appear 

 to pass near it or over its surface. Those currents may often 

 be traced through their whole course around the cell, ascend- 

 ing in one part, descending in another, and sometimes two 

 uniting into one. The structure of each joint of the hair 

 appears to be an outer glassy tube, with longitudinal strise ; 

 between this and the colouring matter the moving fluid with 

 its particles exist. The coloured fluid of the hair seems to be 

 enclosed in a membranous sac, which forms an axis round 

 which the moving fluid revolves. The cytoblast must also be 

 external to the sac, as it is in connection with the currents. 

 (Trans. Soc. Arts, xlix. p. 41). 



The best and most recent observations upon latex do not 

 confirm Professor Schultz's views. Admitting his statements 

 to be essentially true his conclusions are disputed. In par- 

 ticular Professor Mohl has obtained results which make 



