606 (',. II. |i!;i:W y\NI> W. DK M(t|;(!AN. 



steatly invasion of tlic tissues l>y the leriiu'iits, iind tliat tlie 

 area, of tlioir action is always contained vvitliin a protective 

 layer of ao'g'liitiiiated hlood-coi-puscles. It seems pi-oljable 

 that the di<^estive ohuul, when implanted, contains little or 

 no free enzyme, and (jiiickly becomes surrounded by the 

 protective layer oF corpuscles, and that later the enzymes 

 are slowly evolved from the zymogens contained within the 

 cell. The vitality of these cells has been iin])aii-i'd by I'cmoval 

 from their normal connections and by implantation into the 

 muscle tissue, and accoi-dingly they are dissolved l)y the 

 enzymes they have themselves evolved. 



TlIR KEACTroN oi' THK TlSSUKS TO IMPLANTED AgAR JkLLY. 



Sterile agar jelly has no irritative action on the muscle, 

 and so differs From the tissues pi-eviously described. 



Agar jelly may l)e regarded as a physiologically inert 

 substance, and as in these experiments it was made from sea- 

 water in which the Pecten were living, it was approximately 

 of the same salinity as their blood (Dakin, 2), and so was of 

 the same osmotic concentration. Further, the cylindrical 

 rods of agar are remarkably smooth, and if unbroken present 

 no rough surface, except possibly at the extremities. 



One of us (Drew, 4) has shown that in the case of 

 Cardium norvegicujn, the agglutination of the blood- 

 corpuscles (m vitro) is much iuHuenced by the nature of tlu; 

 substance on which they impinge, and that it occurs very 

 much more readily when they come in contact with a rough 

 surface from which a large number of small points may be 

 itnagined to project, than when they impinge on a smooth, 

 polished body. It seems probable that similar conditions 

 obtain in the case of the blood of Pecten maximus. 



In accordance with these properties of the agar jelly, it 

 was found that absolutely no inflammation resulted from its 

 implantation in the muscle. No layer of agglutinated 

 corpuscles was formed round it, and there was no sign of the 

 collection of unusual numbers of the corpuscles in the 



