182 



PHYTOTOMY. 



with a multitude of very fine fibrils, or hairs, which are closed 

 at their extremities, (Keiser^s Grundzuge der Anatomie der 

 Pflanzen, Tab. VI. Fig. 62.) These hairs in particular, with 

 their close and flaggon-shaped extremities, have a considerable 

 resemblance to the first appearances of the absorbent vessels 

 in the small intestines. As the former, like the latter, are 

 shut, we have in them a new proof of the organical perspira- 

 tion we have mentioned, and which takes place, notwithstand- 

 ing the peculiar impermeability of the partition. These 

 hairs are in immediate connection with the cellular texture of 

 the radicle ; and as this first conveys the juice, that has been 

 absorbed, to the sap-vessels, it is evident that the unformed 

 fluids are already considerably changed, before they proceed 

 from the radicle into the root. The entire structure of the 

 radicle is protected by a fine cellular texture which surrounds 

 the sap-vessels in the centre. 



On tlie ends of the radicle we often perceive drops of a 

 fluid, which is of a slimy consistence, and which, in all pro- 

 bability, has been derived from them. 



286. 



Some families of plants of the lower orders, the Ferns, 

 Palms, and Hydrocharidje, as also the Naiadae, instead of 

 these small hairs, have a spongy integument at the extremity 

 of the radicle. We observe it, in the form of a coif, or hood, 

 very distinctly in Lemna and Callitriche. This integu- 

 ment is not porous, but it consists of a very soft cellular 

 texture, which swells out in some small portions, but in other 

 respects is entirely closed. Here also, therefore, takes place 

 the absorbtion through the impervious partitions of the cellu- 

 lar texture. 



287. 



The radix, being the continuation of the stem into the earth, 

 has the same constituent parts with it, but with some differ- 

 ences, which are derived from the covering of the soil. Com- 

 monly the pith is wanting, and the centre of the root consists 

 of a woody kernel. Sometimes, however, it is hollow, and 



