CONNECTIVE TISSUE 53 



testing-wandering' cells, or 'clasmatocytes,' are perhaps to be regarded 

 as varieties of basophilic granulocytes characterized principally by the 

 presence of irregular protoplasmic processes. According to Kite (Jour. 

 Infec. Dis., 15, 2, 1914) the 'clasmatocytes' described for the frog by 

 Ranvier in 1891 are lymphocytes which have protruded pseudopods. 

 Evans classifies them with the 'macrophages' of Metschnikoff. 



TYPES OF CONNECTIVE TISSUE 



The proportions and character of the cells and fibers present in 

 any given connective tissue, to a certain extent determine its character. 

 If the collagenous fibers of connective tissue are closely packed in dense 

 parallel bundles, the elastic fibers being comparatively insignificant in 

 number, the type of connective tissue may then be said to be dense 

 fibrous or white fibrous tissue. 



In elastic tissue on the other hand, the yellow elastic fibers are highly 

 developed, the white fibers forming only insignificant and very delicate 

 sheaths which inclose the coarser elastic fibers. 



Again, it is the variety of delicate connective tissue fiber known as 

 reticulum which preponderates in reticular tissue, and if the meshes of 

 this reticular network become infiltrated by lymphocytes, which then mul- 

 tiply by division until they exceed the other tissue elements, the connective 

 tissue is then said to be of the lymphoid or adenoid variety. Large num- 

 bers of the fixed cells of areolar connective tissue may change into fat cells, 

 the tissue as a whole then forming adipose tissue. In all we distinguish 

 the following varieties of connective tissue: (1) Embryonal; (2) mucous; 

 (3) reticular; (4) loose fibro-elastic or areolar; (5) dense fibrous; (6) 

 dense elastic; (7) adipose; (8) adenoid; (9) cartilage; (10) bone. 



Embryonal Connective Tissue. Embryonal connective tissue (Figs. 

 55 and 56) occurs not only in fetal and infantile life, but also during the 

 regeneration of destroyed connective* tissue areas and in pathological 

 neoplasms. It is distinctly cellular in character. Its cells are spindle- 

 shaped and stellate, are much branched, and through their larger proc- 

 esses they frequently anastomose. 



The fibers are extremely fine; they are not usually arranged in bun- 

 dles, but form a delicate network which permeates the ground substance 

 in every direction. In the very immature types the fibers are all of the 

 collagenous variety ; delicate elastic fibers appear later. The fluid ground 

 substance forms an abundant mass of tissue juice which occupies the 

 meshes of the fibrous net. The earliest developmental stages are ideuti- 



