404 THE CELLULAR MEMBRANE. 



It appears to be composed of membranous laminae, exqui- 

 sitely fine and delicate in their structure, which are so con- 

 nected to each other that they compose cells or cavities of 

 various forms and sizes. 



When these cavities are empty, this arrangement of the cel- 

 lular membrane is not apparent ; but when they are distended 

 by water or air it is very evident. 



The laminae which pass from one contiguous part to another 

 are of different lengths, according to the motions performed by 

 the different parts ; thus, about the muscles and their tendons 

 they are of considerable length, and between the coats of the 

 eye they are very short. 



In some places, these laminae are compressed together, and 

 form a dense membrane somewhat resembling tendon ; but 

 whenever they are separated from each other, they appear 

 pellucid, and extremely delicate. 



The term cell and cellgerm being used by the latest writers 

 on anatomy in a very definite and restricted sense, the name 

 cellular tissue seems to be almost improper for a structure which 

 is ultimately composed of filaments, intricately interwoven, but 

 forming open spaces, and perfectly permeable as shown by the 

 easy transgress of fluids from one part of the body to another. 

 By cell is meant, a closed vesicle, containing a nucleus, whose 

 walls and contents may undergo various changes by the pro- 

 cesses of endosmosis and exosmosis, or which may remain as a 

 cell in the constitution of different tissues. These cells are the 

 primary offspring of the cellgerm, or cytoblast (a nucleus includ- 

 ing a nucleolus) being analogous to the blood globules or corpus- 

 cles which possess the faculty of producing their like, out of the 

 surrounding amorphous fluid or cytoblastema ; the vital fluids 

 containing the elements of all organic formation. Out of such a 

 cell-mass, all the organs in the embryo are developed, and we 

 may still observe similar transformations, in the processes of repro- 

 duction of the different organs. Cells, as such, compose the 

 simpler extra-vascular tissues, as the adipose and pigmentary 

 cells, the horny tissue with its various modifications in the epi- 

 dermis, hair, nails, horns, claws, hoofs, and the epithelium. In 



