TISSUES. 73 



(b.) Complex tissues. 



5. Osseous tissue. 



6. Smooth muscular tissue. 



7. Transversely striated muscular tissue. 



8. Nervous tissue. 



9. The tissue of the blood-vascular glands. 

 10. The tissue of the true glands. 



The organs may be divided like the tissues, into simple and complex. 



To the simple belong : 



(a.) Horny tissue, as the epidermis, the epithelia, hairs, nails, and 

 the lens, which consist solely and wholly of epithelial cells of one kind 

 or another. 



(b.) The true cartilages and the elastic cartilages, which in their inte- 

 rior, with few exceptions, consist only of cartilaginous tissue, though 

 externally they possess a vascular and nervous coat, the perichondrium. 



(c.) The elastic ligaments, consisting of elastic fibres, with some con- 

 nective tissue, and containing only at the surface a few vessels and 

 nerves. 



(d.) The tendons, ligaments, true fibrous membranes, and fibro-carti- 

 lages, containing a preponderance of connective tissue, intermixed with 

 fine elastic fibres, and sometimes cartilage cells in small quantities, and 

 almost entirely devoid of vessels and nerves. 



Complex organs are : 



(e.) The smooth muscles and muscular membranes ; and 



(/.) The transversely striated muscles and muscular membranes, both 

 of which, besides their contractile elements, are abundantly intermingled 

 with connective tissue, nerves, and blood-vessels. 



(g.) The nerves, ganglia, and higher central organs of the nervous 

 system, contain besides gray and white nervous substance, many blood- 

 vessels, and special fibrous investments. 



(h.) The vessels are composed of connective and elastic tissue, muscles 

 and epithelium in various proportions, and are provided with vessels and 

 nerves, only in their outermost layers. 



(i.) The bones and teeth, which, together with their characteristic tis- 

 sues, have peculiar soft structures, containing many vessels and nerves, 

 and the former medulla also. 



(&.) The blood-vascular glands, composed of a peculiar glandular ele- 

 ment, in the form of closed follicles of different kinds, and many blood- 

 vessels ; with nerves also, and with abundant but generally non-con- 

 tractile fibrous tissue. 



(I.) The true glands ; glandular follicles, vesicles or tubes with many 

 vessels, nerves, and investing fibrous tissue. 



(m.) The vascular membranes, as the skin, the mucous, serous, and 

 proper vascular membranes, which in a matrix composed of connective 



