LESSON 22.] CELLS, MEMBRANE, AND FIBEE. 63 



(forms fibres), by which process the lips (say a cut finger) are brought 

 together, and permanently laced by the newly formed fibres. In 

 this operation lymph is thrown out in excess, and the portion of it 

 that cannot be used, dries up, by exposure to the atmosphere, and is 

 invariably of a yellowish color never red thereby showing the 

 absence of the red corpuscles in this process. 



LESSON XXII. 



OF CELLS, MEMBEANE, AND FIBEE. 



369. The history of the vegetable cell has already been given ; 

 the history of the animal cell is in every respect precisely similar. 

 So perfectly identical is the cellular tissue of a plant, and an animal 

 cellular tissue, that the microscope fails to detect a point of differ- 

 ence ; when, too, we consider the number of diverse animal tissues 

 having a cell-structure for their basis, this fact is not a little remark- 

 able. 



Still, there are important differences between them, which the 

 Chemist can detect, although the microscope in this respect is 

 powerless. 



370. We have seen that the cell-wall of a plant is composed of 

 cellulose / the animal cell- wall is equally transparent, and possesses 

 all the other microscopical characteristics, but it is chemically differ- 

 ent ; every animal cell-wall is solely composed of an animal element, 

 namely, Proteine. 



371. Great difference exists in the contents of animal cells ; thus 

 the cells which float in the Chyle, the Lymph, and the Blood, the 

 latter devoid of color, have no single nucleus, but a variable number 

 of scattered particles in the nature of nucleoli (little nuclei), each of 

 which obtains an independent existence by the bursting or absorption 

 of the cell- wall : here, again, is a vegetable parallelism. 



372. The liberated nucleoli float in the fluid, till they, in their 

 turn, mature into perfect cells. 



In animal, as in vegetable cells, the nucleus appears to be the 

 all-important portion of it; the membrane appears to have little 

 else to do than simply containing and isolating it. 



373. In many animal tissues the multiplication of the cells can 



