280 WEN HAM, ON THE CIRCULATION OF THE SAP 



The deportment of the o^ranules during their passage has 

 already been described in the Microscopical Journal for Oct. 

 1853, page 54, by Mr. Lawson, to whom we are indebted for 

 the discovery of the sap-rotation in this interesting object. 

 When the rotation is moderately active, the speed of the 

 granules is about l-40th of an inch per minute ; a motion 

 apparently small until magnified to 800 linear, when each 

 granule is seen to travel round its containing cell, with suf- 

 ficient rapidity, several times during one minute. 



The rotation in one cell does not exert any influence upon 

 the direction of the granules travelling in the immediately 

 adjoining one. The motion is sometimes the same way, but 

 quite as often in the contrary direction. 



The question now is, what is the agent that gives motion 

 to these otherwise inactive granules? I have before remarked 

 that the whole interior of each cell is lined with an investing 

 layer in rapid motion, of a thickness varying from l-20,000th 

 to 1-25, 000th of an inch. This stratum I have ascertained to 

 be entirely composed of a multitude of active corpuscules, 

 diff'ering in size from l-60,000th to l-90,000th of an inch. 

 I am not quite positive about their exact dimensions, for, on 

 account of their gelatinous nature, they do not possess a very 

 definite outline, and are, in consequence, somewhat difficult 

 of measurement. They are not, however, in general, much 

 larger than I have stated. 



If one of the leaves of the Anacharis he placed on a piece 

 of thin glass, with a very small quantity of water, and then 

 torn into minute fragments with two needle-points, and 

 finally covered with another piece of thin glass, on viewing the 

 fluid with an eighth object-glass, it will be seen that it is 

 entirely filled with tliese active corpuscules, exhibiting that 

 vigorous isochronal motion characteristic of molecular ac- 

 tion. 



A weak solution of ammonia rather increases the activity 

 of tliese bodies, but dilute alcohol and acids immediately 

 destroy the movement. 



These combined corpuscules are essentially the principle 

 of the vital movement in the plant, and also the vehicle that 

 causes the rotation of the chlorophyll granules, which are of 

 themselves perfectly passive, and move only in obedience to 

 the direction and control of the corpuscular current ; neither 

 is the presence of the granules at all necessary for the excita- 

 tion of the active principle of circulation, for I have repeatedly 

 seen cells containing not a single granule, in which the circu- 

 lating layer was in a rapid state of progressive motion — in 

 fact, the presence of numerous granules rather tends to retard 



