CHARACTERS OF PIGMENT CELLS. 61 



animals and in embryoes, and here the cells frequently give 

 off branched processes, which communicate with those pro- 

 ceeding from other stellate cells. The fusiform cells are less 

 abundant in the fasciculi of the connective tissue of adults 

 than was formerly supposed. They are remarkably developed 

 in the cornea. In embryonic connective tissue they are very 

 numerous, and repeatedly communicate by means of their 

 processes. 



We also meet with anastomosing stellate cells in the adult 

 in the more independent connective tissue formations, occu- 

 pying the interspaces of the fibrous connective tissue, or in 

 places where fibrous connective tissue is altogether absent. 

 From a general review of the cellular structures found in con- 

 nective tissue, it is apparent that, beginning with the young 

 cell, we have to deal with a series of cells in various stages of 

 development. 



The importance of any statement made in regard to the size 

 and form of the cells, on which so much stress was formerly 

 laid, will be less in proportion to the degree of mobility 

 possessed by the cells when in the perfectly fresh condition. 



It would, however, be decidedly going too far, were we to 

 give up all distinguishing marks derived from the consideration 

 of these points, since all experience tends to show that a dis- 

 tinction must be drawn between processes of protoplasm thrust 

 forth by vital movement, and capable of being again with- 

 drawn, and the fixed outgrowth of cells. The genetic connection 

 existing between the various kinds of cells found in connective 

 tissue, their physiological peculiarities, the chemical and phy- 

 sical alterations which they undergo from their first origin to a 

 certain period of their life, etc., are all questions which require 

 further investigation. 



Lastly, The pigment cells of connective tissue require to be 

 specially mentioned. In Man and the higher Vertebrata they 

 occur only in a few limited spots, but they are much more 

 widely distributed in Amphibia and Fishes, appearing especially 

 in the skin, in the serous membranes, and in the tunica adven- 

 titia of the vessels. 



In these places the pigment may also be found deposited in 

 the form of granules which differ both in shape and colour. 



H 2 



