22 AN"ATOMY AND PHYSIOLOGY OF 



fibres fir&t deposited are already connected into a net-work, as is especially 

 Been in tlie exaaiination of tlie young roots of the PalmB. On tlie otlier 

 hand; tliis conception of the transition of a spu-al vessel into a reticulated 

 vessel is ineonipatil>le witli the mechanical condition of the fibre. When 

 iwo spiral vessels lie upon one another their fibres must cross, since in the 

 majority of cases the fibres of the two vessels run in the same direction 

 (homodromons) ; but we find that when two reticulated vessels lie against 

 one another, the fibres in ibe two vessels are placed transversely, and cor- 

 respond accurately together in position; which could only result from 

 the fibres of the two vascular utricles losing their original spkal direc- 

 tions, and one being pressed down to the right, the other bo the left, imtil 

 tLeir situations should exactly correspond. Who will believe in such a 

 motion of fibres, which are not free but adherent to the vascular utricles, 

 themselves coherent together"? and who bas seen anything of the kind'? 

 A process of this kind might be held to be possible so long as we were 

 ignorant of tbe true structure of the vessel, and believed that the fibre 

 lay free in the cavity of the vessel, an error which formet-ly prevailed ex- 

 tensively, and which one would not have expected to have still met with 

 in a writing of Schleiden's ("^e^^?m^e," i. 188). And if the incredible 

 statement, that the fibre performed such a journey over one side of the 

 vessel, were actually assumed to be true, how should the prolongations of 

 it over the other sides of the vessel behave ? Would these tear away or 

 be pulled backwards and forwards, to restore by their more oblique posi- 

 tion what was lost in their spiral course over the other side 1 Instead of 

 the confusion which must necessarily arise from this, we meet with the 

 most beautiful order. If the lateral walls of the vessel are in contact 

 with cells, we find its pits corresponding with those of the cells ; if one 

 part of a vessel is connected with another vessel we meet with hoiizontal, 

 slit-like pits. Thus we see clearly that one elementary organ influences 

 the organization of an adjacent one in a definite manner, but we are no- 

 where able to observe, that an organ already developed to a certain extent 

 allows its already organized parts to perform movements in order to place 

 themselves opposite the parts of the neighbouring organs. Since none of 

 these matters can be seen, the processes are referred back by Schleiden to 

 a time at which the observation is impossible. Thus he says f^' Grwndz. 

 der wiss. Botamk^' i. 228^), it seems to him very probable that the spiral is 

 in existence long before it is visible under our optical insti^uments, since it 

 is composed at first of a substance which does not differ optically from the 

 ccU-wall and cell-contents ; hence, many forms might be referred to the 

 spiral only at that epoch, if we assume that the intermediate stages were 

 run through before the structure was yet visible. I readily allow the 

 author to speculate as to the course of fibres which cannot be seen, but I 

 must be excused from following him into this region. Yalentin, indeed, who 

 originated the theory of the expansion of the spiral fibres in all directions 

 {^^Eep,f. Anat and Fhys^ i. 88), believed that this could be demonstrated 

 by observed facts, for he stated that he had found the secondary mem- 

 bmne making its first appearance in the form of a granular substance, the 

 granules of which at first exhibited no definite order, but were subse- 

 quently arranged into spirals, and became connected into the spiral lines 

 which might be distinguished on the completely formed membrane ; a 

 view which has not acquired confirmation from any subsequent observer, 



