56 LECTURE II. 



cells have attained specific, higher forms of development, 

 by means of which their constitution has acquired a 

 type entirely peculiar ; indeed, in part so peculiar, as to 

 appertain exclusively to the animal economy. These are 

 the tissues which are really characteristic of animals, 

 although a few among them exhibit transitions of vege- 

 table forms. To this class belong the nervous and 

 muscular systems, the vessels and the blood. Herewith 

 is the list of tissues concluded. 



You must now proceed to consider, in what respect, 

 in this summary of the result of histological researches, 

 a contrast is afforded to what was formerly, chiefly in 

 imitation of Bichat, regarded as constituting a tissue. 

 Bichat's tissues would, for the most part, not so much 

 represent what we now regard as the subjects of General 

 Histology, as what we must rather designate as be- 

 longing to Special Histology. For, if we regard the 

 tissues in the light they were formerly regarded ; if we, 

 for example, separate tendons, bones, and facise, from 

 one another, we then obtain an extraordinary variety 

 of categories (Bichat had twenty-one), but there are 

 not quite as many simple forms of tissue to correspond 

 to them. 



In accordance with modern notions, the whole domain 

 of anatomy should first be divided into the categories of 

 General Histology (tissues properly so called). Special 

 Histology, ;then, takes up the instances, in which a com- 

 bination of tissues, sometimes very different, into a 

 single whole (organ) takes place. Thus we speak, for 

 example, of osseous tissue ; but this tissue, the tela 

 ossea of general histology, does not of itself form bone, 

 for no bone consists entirely of tela ossea, but it has 

 necessarily superadded at least periosteum and vessels. 

 Nay, and from this simple conception of a bone, every 

 bone of considerable size, for example, a long bone. 



