Vegetable Tissue. , 229 



h s been seen to grow in length at the rate of an inch and a half a 

 lav The leaf of the Urania Speciosa has been found, by Mul- 

 der to lengthen at the rate of from one and a half to three and a 

 half lines per hour, and even as much as from four to five inches 

 oer day. This may be computed to equal the development of at 

 least four or five thousand cellules per hour. But the most re- 

 markable instances of this sort are to be found in the Mushroom 

 tribe which in all cases develope with surprising rapidity. It is 

 stated bv Junghuns, that he has known the Borista Gigantium, in 

 damp, warm weather, grow in a single night from the size of a 

 mere point to that of a huge gourd ; supposing it, at a moderate 

 estimate, to have grown in the course of twelve hours, its cellules 

 must have developed at the rate of near 4,000,000,000 per hour, 

 or more than thirty-six millions per minute. 



Woody fibre consists of very slender, transparent, membranous 

 tubes, tapering acutely at each end, lying in bundles, and, like 

 the cellular tissue, having no direct communication with each 

 other, except by invisible pores. It may at all times be known 

 by its elongated figure and extremely attenuated character ; usu- 

 ally it has no sort of markings on its surface, except occasionally 

 a particle or two of greenish matter in its inside ; sometimes, 

 however, it is covered with spots that have been mistaken for 

 pores, and that give it a peculiar character. Generally while 

 cellular tissue is brittle and has little or no cohesion, woody 

 fibre has great tenacity and strength, whence its capability of 

 being manufactured into linen. Everything prepared of flax, 

 hemp, and the like, is composed of woody fibre ; of this there 

 are three distinct kinds : 1st. That in which the walls are not 

 occupied with granules or glands sticking to them, or in which 

 the former are of very rare occurrence. This is the finest and com- 

 monest of all ; and is also the most genuine state of woody fibre. 

 2d. Those in which the walls have uniformly a considerable 

 number of granules of regular size, sticking to them in a scattered 

 manner. 3d. The glandular, which has hitherto only been noticed 

 in the Conifera, in which it is uniformly found in every species ; 

 its dimensions are more considerable than either of the two last 

 mentioned forms. Woody fibre constitutes a considerable propor- 

 tion of the ligneous part of all plants ; it is common in bark, and 

 forms the principal portions of the veins of leaves, to which it 

 gives stiffness and tenacity. 



