THE 



GENERAL ANATOMY OF THE TISSUES. 



I.— OF THE ELEMENTARY PARTS. 



If the solid and fluid constituents of the human body be 

 examined with the aid of strong magnifying powers, it appears 

 at once that the smallest parts which they exhibit to the naked 

 eye, as granules, fibres, tubes, membranes, &c, ni'e not the 

 ultimate elements in respect of form, but on the contrary, 

 that all, in conjunction with an universally distributed, fluid, 

 semifluid or even solid, homogeneous, uniting substance, 

 contain minute particles which differ in different organs but in 

 the same organs have always a similar appearance. There 

 are various kinds of these so-called elementary parts, simple 

 and compound. The simplest are quite homogeneous, without 

 any trace of their being composed of heterogeneous portions 

 and are nearly allied to the inorganic forms, the crystalline 

 granules and crystals, which also occur in the animal organism. 

 Others already show that they have suffered a differentiation 

 into an investment and determinate, though homogeneous 

 contents : in others again, the contents present differences. 

 The most important among all these forms, which may be 

 comprehended under the general title of " simple elementary 

 parts," are the cells, which not only form the starting-point of 

 every animal and vegetable organism, but also, either as cells 

 or after having undergone manifold metamorphoses, make up 

 the body of the perfect animal, and in the simplest animal 

 and vegetable formations (unicellular animals and plants), 

 even enjoy an independent existence. Compared with cells, 

 all other simple elementary parts have quite a subordinate 



