COAGULATION OF BLOOD OF ARTHROPODS. 317 



facts observed during the second coagulation can be explained 

 through the hypothesis of the action of a fibrin ferment present 

 in the blood cells and in the muscle of the lobster, which how- 

 ever is not present in the blood cells or in the muscle of certain 

 vertebrates. This points to a multiplicity of fibrin ferments in 

 different species of animals and points to the identity of the fer- 

 ment in different tissues of the same species of animals. This 

 specificity in the one case and the want of it in the other case 

 corresponds to a similar specificity and want of specificity as has 

 been found to exist with the precipitins obtained through injection 

 of certain body fluids or albuminous substances into different 

 species of animals. 



7. Potassium cyanide, urea and solutions of peptone inhibit 

 the second coagulation. If these substances are add to the serum 

 their inhibiting influence is in a reverse proportion to thire 

 strength if they act directly upon the fibrin which contains the 

 ferment. Potassium cyanide has the strongest, peptone the 

 weakest action upon the fibrin, and conversely, peptone has the 

 strongest and potassium cyanide the weakest action on being 

 mixed with serum. 



8. The necessity of the presence of calcium for the second 

 coagulation can be easily proved. Ammonium chloride has a 

 stronger inhibiting action on the second coagulation than sodium 

 chloride. 



9. Mechanical agencies, namely, pressure and traction, change 

 the cell protoplasm into a system of fibers which cannot be dis- 

 tinguished in its physical properties and appearances from the 

 extra-cellular fibers. The cell granules disappear under the in- 

 fluence of traction and pressure, just as the granules disappear 

 spontaneously in the cells during coagulation of the blood. By 

 traction and pressure exerted upon the blood serum free from cells, 

 similar fibrillar structures can be produced as in the protoplasm of 

 the cell. The fibrillar structure of the protoplasm seems therefore 

 to be a secondary condition, produced by mechanical influence 

 upon albuminous substances which maybe common to the proto- 

 plasm of the cell and to solutions of certain albuminous substances. 



10. By pressure and traction the cell protoplasm can be 

 changed into fibers whose arrangement is determined by the 



