m> PHYSIOLOGY CHAP. 



of the migratory cells, but his work was ohviously (as stated by 

 P. Heger) " the true introduction to that associated three years 

 later with the name of Cohnheim." 



We must now briefly describe the facts that can be observed 

 without difficulty either in the mesentery or the tongue of the 

 frog, after it has been paralysed with curare, or its spinal cord 

 destroyed, when a certain amount of neuro-paralytic dilatation of 

 the small arteries is produced. 



When the peritoneum is exposed to air, the circulation in the 

 peritoneal vessels exhibits a marked retardation after about an 

 hour, so that (with a magnification of 200 to oOO diameters) the 

 corpuscles can not only be seen distinctly circulating in the 

 capillaries and veins, but also in quicker motion within the small 

 arteries. 



This delay has no sooner begun than a partial block and 



Flo. 49. Cohnheim's apparatus for studying the course of the circulatory phenomena 

 in inllummution of frog's peritoneum. 



accumulation of corpuscles will be observed in the capillaries^ 

 which gradually disappears in some places to reappear in others. 



In the small veins the most conspicuous feature is the im- 

 mobilisation of the leucocytes on the internal walls of the vessels. 



As they leave the capillary network, they advance with a rotary 

 motion along the wall of the vein, and become fixed in contact with 

 those that are already immobilised. Little by little they cover the 

 entire internal surface of the small veins, forming a hollow cylinder 

 of motionless leucocytes surrounding the cylinder of moving 

 erythrocytes. 



On continuing to observe the leucocytes clinging to the walls 

 of the small veins and capillaries, it is possible in about two hours 

 from the beginning of the experiment to catch the corpuscles in 

 flagrante, in the very act of traversing the vessel walls to penetrate 

 into the meshes of the connective tissue or into a lymph sheath, or 

 the surface of the serosa. Here and there on the outside of the vessel 

 an irregular lump of protoplasm is seen, which forms a sort of hernia, 

 and is continuous with the iutra vascular portion of the protoplasm 

 of the corpuscles. The external portion of the corpuscle becomes 



