50 DEVELOPMENT OF CONNECTIVE-TISSUE FIBERS. 



to the manner of the. formation of the connective-tissue fibrils in the embryo 

 from results which are so obviously due to injured cells as are those of Loeb's 

 experiments. However, there is a striking resemblance between the fibrous tissue 

 obtained by Baitsell by means of a modification of the fibrin clot and the fibrous 

 tissue of the embryo. 



BaitselPs (1916) paper on wound-healing, in which he finds that very shortly 

 after a wound has been made in the skin of a frog, fibrin fibers, which resemble 

 connective-tissue fibrils, are deposited, and that these fibers persist and take part 

 in the formation of the cutaneous tissue, opens the exceedingly interesting ques- 

 tion as to whether what takes place in the process of wound-healing can be in any 

 way comparable to the behavior of normal developing tissue. 



So far as can be gathered from Isaacs's (1916) incomplete report of his obser- 

 vations upon the living connective-tissue fibers, his results correspond more or 

 less with those of Loeb that is, that various strains cause the intercellular sub- 

 stance to form fibrillse. Just what part the cells play in this formation it is 

 difficult to understand. Isaacs does not say that the cells form an enzyme, as 

 Loeb claims, but states that the movements of the connective-tissue cells probably 

 effect the distribution of the material through chemical or other action and cause 

 the fibrillated structures of the adult fiber. From Isaacs's brief report it is evident 

 that he had performed numerous experiments with the living connective tissue, 

 and it is hoped that his complete paper will clear up many points. 



Ferguson's (1912) observations upon the living connective-tissue cells in the 

 fins of fish embryos are extremely interesting, since by his method the connective- 

 tissue cells were studied under entirely normal conditions. Since there has been 

 some question as to whether fibers actually exist or whether they are merely 

 coagulations of a colloid within the tissue due to abnormal conditions, it is inter- 

 esting to note that Ferguson describes fibers as well as cells as existing in the 

 living embryo. He found, by the aid of preparation stained by Bielschowsky's 

 method, that the fibers arise within the cell. Unfortunately he was not able to 

 see the fibers in the embryonic cells of the living embryo and to determine whether 

 they become separated from the cells, or how this takes place. His observations 

 upon the movements of the connective-tissue cells show that the round and 

 stellate cells may move up to and stretch along a fiber as a very thin, long spindle 

 cell, and in a few cases he observed such a spindle cell to become stellate again. 



Ebeling (1913) has for a period of two years or more kept alive certain of 

 the cultures started by Carrel. The growth of these cultures consists mainly of 

 connective tissue, and Ebeling claims that connective tissue may have a permanent 

 life outside the organism when properly cared for. The method of keeping the 

 culture alive is as follows: The entire culture in its plasma clot is freed from the 

 cover-slip and washed in Locke's solution to remove any waste products and is 

 then cut into four or more pieces, and each of these pieces is again explanted into 

 a drop of fresh plasma. This procedure is carried out every other day; although 

 many of the cultures die, a few survive and grow, and are again explanted as 

 described above. In all probability there is no differentiation of the connective 

 tissue into fibrils or fibers, as Ebeling describes the growth as though it consisted 



