248 IMMUNO-CATALYSIS 



Clean, and McClean and Hale. McClean (1936) found that the activ- 

 ity of the permeability factor of the welchii filtrate was not inhibited 

 by an amount of antitoxin sufficient to neutralize the specific toxin 

 action. It was noticed that the addition of the antitoxin caused a 

 diminution in the immediate diffusion of the intracutaneous bleb, 

 though the increased spread of toxins or ink used as indicator was 

 never completely inhibited. Normal horse serum in the same concen- 

 tration as the antitoxic serum did not prevent immediate diffusion, 

 and it was concluded therefore that the inhibition might be due to an 

 antibody. This apparent incomplete inhibition might have been due 

 to the toxic effect of the toxin present in the filtrate, as was observed 

 by Chain and Duthie (1940). In contrast, the immune sera prepared 

 by McClean (1936) in rabbits by subcutaneous injections of welchii 

 toxoid followed by toxin during a period of two months almost com- 

 pletely inhibited the activity of the diffusing factor. One volume of 

 a 1 : 10 dilution of the antitoxic serum caused inhibition of the spread 

 of a five times minimal diffusing solution. All four immune rabbits 

 were found to suppress the immediate diffusion of an intracutaneous 

 bleb in their skins, showing that animals possessed immunity against 

 the diffusing factor. Anti-diffusing rabbit serum against welchii toxoid 

 exercised no inhibitory action on the testicular extracts, which showed 

 a high degree of specificity. 



McClean and Hale (1941) likewise found that antihyaluronidase 

 serum neutralized the enzymic activity. In the observation on the 

 liberation of N-acetylglucosamine, the enzyme from vihrion se^ptique 

 was the only one used. In observations on the viscosity-reducing 

 activity, both CI. welchii and vihrion seftique enzymes were set up 

 with homologous and heterologous antiserum and normal serum, using 

 a substrate of mucoprotein derived from umbilical cord. Equal vol- 

 umes of undiluted serum and the enzyme preparations were mixed, 

 and left at room temperature for 30 minutes before addition to the 

 substrate. The amount of acetylglucosamine liberated was estimated 

 after an 18 hour incubation at 37 °C. In both experiments, the inhibi- 

 tion of enzymic activity was complete and strictly specific; the heter- 

 ologous antisera and normal serum exerted no effect. 



The diffusing activity of these enzymes in the skin occurred at a 

 much higher dilution than that at which any in vitro viscosity-reducing 

 activity could be demonstrated. These antisera only completely in- 



