THE CONNECTIVE TISSUES. 1 27 



fibrils. Such preparations are also useful in studying the action of reagents 

 (see below). 



The substance resembling mucin which cements the fibrillae together 

 is soluble in lime-water and baryta-water a circumstance made use of 

 and recommended by Rollet (72, II) as a method for the isolation of 

 connective-tissue fibrils. In necrotic tissue the fibers show a degenera- 

 tion into fibrils (Ranvier, 89). 



If connective tissue be heated in water or dilute acids to 120 C., and 

 the fluid then filtered, a solution is obtained from which collagen can be 

 precipitated by means of alcohol. This is insoluble in cold water, alcohol, 

 and ether, but is soluble in hot water and when dissolved in the latter and 

 cooled, becomes transformed into a gelatinous substance. Unlike mucin 

 and chondrin this substance does not precipitate on the addition of acetic 

 and mineral acids. Tannic acid and corrosive sublimate will cause pre- 

 cipitation, as also in the case of chondrin, but not with mucin (vid. also 

 Hoppe-Seyler). 



Elastic tissue, may be obtained by treating connective tissue with 

 potassium hydrate solution, and if the alveoli of the lungs be treated 

 for some time with this reagent, very small elastic fibers can be obtained. 

 By this means the connective-tissue fibers are dissolved, but not the elastic 

 fibers. Particularly coarse fibers are found in the ligamenta subflava. 



According to Kiihne, connective and elastic tissues are differ- 

 ently affected by trypsin digestion /. e., alkaline glycerin-pancreas 

 extract at 35 C. white fibrous connective tissue being resolved into 

 fibrils, while elastic tissue is entirely dissolved. 



To F. P. Mall also belongs the credit for a few data, which we 

 insert, as to the different reactions which various connective-tissue sub- 

 stances show when treated by the same reagents. 



When a tendon is boiled it becomes shorter, but if it be fixed before 

 boiling, there is no change. Adenoid reticulum shrinks when boiled, but 

 after a short time swells, and finally dissolves. Both tendon and adenoid 

 reticulum shrink at 70 C. If, however, they be first treated with a 

 0.5% solution of osmic acid, the shrinkage will not take place until 

 95 C. is reached. If the reticulum or the tendon has become shrunken 

 through heat, they are easily digested with pancreatin, and putrefy very 

 readily. Tendon fibers do not become swollen in glacial acetic acid, 

 either concentrated or ;n strengths of 0.05% or less, but in strengths 

 of 0.5% to 25 f / c they swell, and if placed in a 25% solution they will 

 dissolve in twenty-four nours. They also swell in hydrochloric acid in 

 strengths of o.i ( / c to 6%. In strengths of 6% to 25% the fibers remain 

 unchanged for some time, and only dissolve in a concentrated solution 

 of this acid. Reticulated tissue, on the other hand, swells in a 3% 

 hydrochloric acid solution, but remains unchanged in strengths of 3 / c to 

 lo 1 /^. It dissolves in twenty-four hours in solutions of 25^ and over. 

 After treatment with a dilute solution of acid, tendon dissolves more rapidly 

 on boiling than does reticular tissue. 



Tendon exposed to the action of the gastric juice of a dog does not 

 dissolve more rapidly than elastic tissue ; but if placed in an artificial solu- 

 tion of gastric juice, tendon dissolves first, then reticular tissue, and finally 

 elastic fibers. Pancreatin affects neither tendon nor reticulated tissue, but 

 if boiled, both tissues are easily digested by its action. If taken out of 

 the body, neither tendon nor reticulum will become affected by putre- 

 faction. In the body, however, and especially at high temperatures 

 (37 C.), both tissues are decomposed within a few days. 



