348 THE MICROSCOPE. 



being composed of oil, surrounded by a covering of casein and dis- 

 solved fibrin, have been shown to attract a covering of albumen. 



In this way the chyle, for instance, is taken as food into the 

 body. The chyle is composed of protein compounds and fatty mat- 

 ters, which are reduced to a pulp by the digestive process ; the pro- 

 tein compounds being converted into albuminous matters. The villi 

 throughout the intestinal canal are permeable to these fluids ; the oily 

 particles meeting with a protein compound, are attracted to them, form- 

 ing a covering; and so an elementary granule is formed. In their sub- 

 sequent development, cells, when fully formed, never lose their cha- 

 racter as cells while they exist ; but they may dissolve other cells before 

 they are changed into certain tissues. Cells may receive additional 

 parts, which may remain as such, or form tissues ; such are termed 

 complicated cells: nerves and muscular fibre are formed from these. 

 Examples of cells that undergo no further metamorphosis after ful] 

 development are found in the cells of the epithelium, epidermis, and 

 in the corpuscles of the blood. The elementary constituents of glands 

 are cells, and the fluids are absorbed by them : cells are the greal 

 agents of absorption and secretion. 



Change of Cells into Tissues. This may take place by a joining 

 together or coalescence of cells in a rudimentary state. Cells may 

 meet, and at the point of contact coalesce and run into each other, thus 

 forming a tube ; indeed in this manner minute tubular structures are 

 formed. Another mode is : cells aggregate into a mass, and at the 

 point of contact run into each other, thus producing a multilocular 

 cavity. Glandular structures are formed in this way. Membrane is 

 formed of a deposit from the cytoblastema ; before the cell-membrane 

 is formed, the substance from the cytoblastema coalesces with those 

 particles close at hand, thus forming a delicate film-like membrane, 

 This membrane Wharton Jones calls endosmotic, or retentive mem- 

 brane. We may have the cells coalesce to form a filament or fibre. 

 The nucleus may disappear, or form another structure. Where rege- 

 neration of tissue is proceeding, there is found a larger number oi 

 granules. 



Multiplication of Cells. Cells may be formed in cytoblastema inde- 

 pendent of any pre-existing cells : this is indeed an instance of that 

 mysterious agency designated spontaneous generation. As an example 

 of independent formation, we may instance the epithelium and epider- 

 moid cells, corpuscles of the blood, and other juices of the body. Cells 

 are formed from cells in three ways. First, there is gemmiparous 

 generation, that is to say, sprouts occur from previous cells and be- 



