186 MORPHOLOGY. 



is so essential to the signification of the whole, and is so easily recognised, 

 as in the case of Sphagnum, where it may with the greatest ease be 

 isolated long before the origin of the cellular tissue. In like manner, 

 the delicate cellular tissue which necessarily precedes the formation of 

 the spiral fibres, and, according to my views, is far more essential than 

 the latter, has been treated as a secondary matter by most observers, 

 owing to the prejudice they had once adopted of considering the whole 

 organ as a pollen-vesicle, and the contents as the matter of fructification 

 (fovilla) ; entangling themselves in confusion in spite of their own senses. 

 The spiral fibres have elicited the most observation, owing to the mo- 

 tion they manifest ; and they have thus been elevated to the rank of 

 spermatic animalcules. In the course of my own careful examinations of 

 Polytrichum, I have never been able to discover this motion when no 

 water was applied upon the object-stage. When water was present, the 

 fibres exhibited a rapid motion about the axis of the spiral, on which 

 the fibre freed from the cell naturally assumed a progressive motion, in 

 accordance with the law of the archimedean screw ; I have never, like 

 other observers, succeeded in detecting another motion, as, for instance, a 

 change of the convolutions. As far as the form is concerned, I found 

 fibres which had a spherical head at one extremity, or an elongated swell- 

 ing gradually merging in the fibre, or a spherical protruberance below 

 the other extremity of the fibre, or finally a spherical head with, some 

 distance from it, an elongated swelling and, further below again, another 

 spherical swelling. I hold all these forms, of which the last-named were of 

 the least frequent occurrence, as mere unimportant irregularities occasioned 

 by the adhesion of mucus, and not to be the heads of supposed spermatic 

 animalculae. I have also observed, where a simple head was present, that 

 there was as often a progressive motion with the pointed end forward 

 as the reverse. (See Plate II. figs. 9. and 10., with the explanation). 

 The circumstantial description of the views of those who suppose that 

 they have here found spermatic animalcule may be met with in Meyen *, 

 where the discrepancies occurring in the observations of others are re- 

 marked upon. 



I will venture upon a supposition regarding the morphological signifi- 

 cation of these parts when I speak of the ovule of Phanerogamia ; of 

 their physiological importance we know as yet nothing. 



103. The structure of Mosses also is still very simple. The 

 stem exhibits in most cases a closed circle of elongated cells, some 

 narrower and very thick-walled, others wider and thin-walled 

 (circle of vascular bundles), separating the enclosed parenchyma- 

 tous mass (medulla) from the outer portion (cortex). The leaves 

 mostly consist of a simple layer of tabular parenchymatous cells, 

 which have the lateral walls frequently porous, as Dicranum. The 

 upper and lower walls not unfrequently exhibit a papillose pro- 

 jecting thickening, as in Ortliotrichum crispum. The nerve con- 

 sists either only of a few layers of somewhat more elongated cells, 

 or of two bundles of elongated thick-walled cells, which arrange 



subject, and which in the present, advancing state of science, may thus place us beyond 

 the reach of all the philological dilettante, with their ostensibly scientific remodelling 

 of technical terms, and necessarily resulting increased uncertainty and diffuseness of 

 terminology. 



* Meyen, Physiologic, vol. iii. p. 208. 



