324 



singular movetneiits of these molecules are still more clearly seen. These atoms, from 

 their freedom of motion, are arranged indiscriminately in the interior of the vessel, but 

 in a short time some of them enlarge, and then transmit a little light, which, on ac- 

 count of their minute dimensions, is not suffered to pass as a white pencil, hut is de- 

 composed in its course, the granule thereby becoming of a greenish hue. The granules 

 exhibiting this greenish hue are now in a fit state to enter into the composition of the 

 fibre that is to exist in the interior of the membranous tube, and in a spiral vessel this 

 is the manner in which this act is accomplished. 



" The granules which are in active motion in the viscid fluid near one of the ends 

 become severally attracted to the inner wall of the vessel, beginning at the very point; 

 those granules first attracted appear as if cemented to the spot, by the viscid fluid in 

 that direction losing some of its watery character, for there appears a string of a whit- 

 ish colour, besides granules, in the line which the fibre is to occupy. As the other gra- 

 nules are attracted to those already fixed in an inclined direction, the spiral course is 

 soon to be seen, and the same action progressively goes on from the end it began to- 

 wards the other, avound the interior of the tube in the form of a spiral ; the fibre being 

 produced, like a root, by having the new matter added continually to the growing point, 

 thereby causing its gradual elongation. 



" This action is not throughout the vessel at the same instant, for I have witnessed 

 a vessel having one half laid down with fibre, and in the other part the operation had 

 not been commenced. When the granules have arranged themselves throughout the 

 whole length of the tube, those which were first deposited, and had then some slightly 

 visible space between them, have by this time been reinforced by others or nourished 

 by the contents of the vessel, so that that space is obliterated, the fibre beginning to 

 assume a thread-like shape with defined borders, and sufiiciently large to allow of the 

 transmission of white light. When this same action has progressed throughout the 

 entire vessel, the transparency begins to be restored, and what is singular, the entire 

 mass of granules has completely disappeared, appearing as if the exact number and no 

 more had been generated to form the fibre. After the vessel has reached maturity, the 

 liquid contents themselves become absorbed, as happens in the cells of the pith, and the 

 vessel is then empty ; and probably from being seen at difierent periods of its existence 

 in these difiierent states, sometimes full and at others empty, may account for the dis- 

 crepancies existing among botanists as to the functions these vessels perform." — p. 5. 



It appears scarcely necessary to follow the author through the re- 

 marks which succeed the passage above quoted ; a summary of his 

 views on the direction of vegetable fibre, will, however, we trust, be 

 highly acceptable to physiological botanists. 



" It appears to me that the only theory capable of explaining the direction of the 

 fibre, is one that will apply to some peculiar laws existing between the granules them- 

 selves and between the granules and the vital force residing in the vessel or cell in 

 which they are contained. There can be no doubt that at first the granules are in the 

 jelly, consequently as they become sufficiently developed they acquire freedom of mo- 

 tion, and attraction commences between the wall of the cell and the granules, and it 

 can be easily imagined how these numerous atoms may be induced to approach to the 

 circumference of the vessel, but the diflBculty of the proposition is to account for their 

 doing so in a spiral or other determinate form, and always of the same figure in the 

 sartic situation in the same plant. 



