Report of the Progress of Vegetable Physiology in 1836. 525 



a very distinct manner, and a great number of new data which 

 he had already made known in earlier writings have been 

 treated more at large. In reply to those botanists who are 

 of opinion that the spiral tubes convey air, because they had 

 observed that air plainly proceeded from them, Link remarks, 

 that the intestinal canal of animals is also not always full, but 

 frequently contains air. 



Gaudichaud * also has again confirmed a phenomenon, 

 which had previously been described by various travellers, 

 and which speaks very determinately for the sap conduction of 

 the spiral tubes. For if we cut one of these Liane plants 

 possessing great spiral tubes, and at a time when the sap is 

 ascending, a great quantity of sap flows out from the surfaces 

 of the section; that this sap does really proceed from the aper- 

 tures of the spiral tubes has been observed by myself, and also 

 by many other persons. Gaudichaud made his experiments on 

 Cissus hydrophora, a new species which grows in the environs 

 of Rio de Janeiro. A Liane stem of 15 — 18 lines in diameter 

 was cut right through ; the surfaces of the section were moist, 

 no water ran out, excepting a few drops which fell from the 

 upper surface. A small portion of from 15 to 18 inches was cut 

 off' from the basis of the upper end, and placed in a vertical di- 

 rection, and immediately clear water came out in great quan- 

 tity ; various sections from the lower end of the stem exhibited 

 the same phenomenon. The flowing out of the sap however 

 proceeded more slowly ; it just trickled down from both ends, 

 as soon as the severed portion of the end was held in a hori- 

 zontal direction. A portion of 15 inches long byfrom 14 to 15 

 in diameter was cut off from another stem of the same plant ; 

 this gave two ounces of water. From a second piece of the 

 same length from the upper end of the stem Gaudichaud ob- 

 tained rather less water; and this diminution in the flow of 

 water became the more considerable the further the severed 

 end was situated from the base of the stem. On the day fol- 

 lowing that on which the stem had been cut, the surface of 

 the section of the lower end, which was still standing in the 

 ground, exhibited no efflux of sap: the whole end from 5 to 6 

 inches below the surface of the section was dry. Gaudichaud 

 also takes this occasion to mention the causes of the ascent of 

 the sap in general ; he thinks it possible to divide the forces 

 which cause this phenomenon of vegetable life into external 

 and internal forces. To the external forces would belong 

 atmospheric pressure, heat, solar light, &c. The internal 

 forces would have to be subdivided into nutritive and secretive 



* Observ. sur V Ascension de la Seve dans une Liane, et Description de cctte 

 nouvellc cspecc de Cissus. — Ann. des Scien. Nat. 



