COAGULATION OF BLOOD OF ARTHROPODS. 313 



They also are sticky. A cell, hanging on a fiber after coagula- 

 tion of the blood has taken place, sticks to the surface of the 

 slide ; after having sent out processes, if as a result of outside 

 motion a pseudopoclium of the cell touches the surface of the 

 glass. 



Very similar fibrils can be produced if we subject the blood 

 serum of Liiniilns or lobster to the same mechanical agencies. 

 It usually however needs more exertion to obtain the same result 

 from these colloidal solutions than from the cells. 



V. 



Certain analogies may be pointed out which exist between 

 certain processes during coagulation of the blood and certain 

 other phenomena. 



(a) Inside of the body blood corpuscles have an oval shape and 

 do not send out pseudopodia. After having left the body certain 

 changes in the environment take place, the blood cells send out 

 pseudopodia, and somewhat later they begin to spread out over 

 the whole surface of the slide, forming one continuous network. 

 We see a certain analogy between this process and the emigra- 

 tion of leucocytes under so-called inflammatory conditions. 



The changes which lead to the spreading out of the blood 

 corpuscles of arthropods cannot, under the given conditions, be 

 determined by chemotropic influences acting from certain direc- 

 tions. The chemical conditions on the slide are the same on. all 

 sides ; nevertheless, the cells move and spread out. Inflammatory 

 conditions in the higher animals also mean a change of the nor- 

 mal environment brought by toxic or other causes. Thus it 

 may be that the leucocytes of vertebrates do not migrate pri- 

 marily under the influence of chemotactically acting substances, 

 but under the influence of certain physico-chemical factors which 

 bring about changes in the state of the protoplasm of these cells ; 

 direct chemical stimulants may be added secondarily. 



(//) During regenerative processes of the epithelium movements 

 of the cells take place independent of preceding cell multiplication. 

 The epithelial cells under these conditions usually move in con- 

 tact with solid bodies, parts of which, as I have previously shown, 

 may be taken into the cell body itself. It can be observed under 



