585 



essential to the students of medicine, and to impart to it a tone and a 

 vigour which will be of the highest moment to his future investiga- 

 tions." "In the prosecution of his physiolo- 

 gical researches, it is of the highest importance that the medical man 

 should be conversant with the phenomena exhibited by plants. For 

 no one can be reckoned a scientific physiologist who does not embrace 

 within the range of his inquiries all classes of animated beings ; and 

 the more extended his views, the more certain and comprehensive 

 will be his generalizations." 



In remarks bearing on ' cyclosis,' the Author writes thus: — "The 

 elaborated sap is sometimes clear and transparent, at other times it is 

 milky or variously coloured and opaque. By Schultz it has been 

 called latex, and the vessels transmitting it have been denominated 

 laticiferous. The latex contains granules which exhibit certain 

 movements under the microscope. These were first noticed by 

 Schultz, who has written a very elaborate treatise on the subject." 



" Schultz looks upon the latex as a fluid of vital importance, 



and similar to the blood in animals. His views are opposed by 

 Mohl, Tristan, and Treviranus, who consider the latex as a granular 

 fluid containing oil, resin, and caoutchouc, which exhibits molecular 

 movements only when injury is done to the vessels containing it." 



" The plants in which the movements are best observed, are 



those in which the latex is milky or coloured, such as various species 

 of Ficus, Euphorbia, and Chelidonium. In fig. 223 [we cannot ex- 

 tract the woodcut here] there is represented a small fragment of a 

 leaf of Chelidonium majus (celandine) which shows the currents of 

 orange granules in the laticiferous vessels, their direction being indi- 

 cated by arrows. From observations made last summer, I am dis- 

 posed to agree with Schultz's statements. It is true, as Mohl remarks, 

 that any injury done to the part examined causes peculiar oscillatory 

 movements, which speedily cease. Thus, if the young unexpanded 

 sepal of the Celandine is removed from the plant and put under the 

 microscope, or if the inner lining of the young stipule of Ficus elas- 

 tica be treated in a similar manner, very obvious motion is seen in 

 the granular contents of the vessels, and this motion is affected by 

 pricking the vessels or by pressure. In order to avoid fallacy, how- 

 ever, I applied the microscope to the stipules of Ficus elastica, while 

 still attached to the plant and uninjured; and I remarked that, while 

 pressure with any blunt object on the stipule caused a marked oscil- 

 lation in the vessels showing their continuity, there could, neverthe- 

 less, be observed a regular movement from the apex towards the base, 

 Vol. hi. 4 g 



