RELATION OF SKIN TO NONSPECIFIC RESISTANCE 129 



between antibody content and skin reactivity. Then it was observed 

 that the reactivity of the skin could be inhibited by injections of 

 various kinds the heterologous and homologous serums, colloidal 

 metals, starch, in fact after nonspecific injections of various kinds. 



Luithlen took up the experimental study of the alteration of skin 

 reactivity from the vascular side. Using croton oil as an irritant he 

 has observed that after the injection of normal serum of any kind 

 homologous and heterologous after plasma injections or blood 

 transfusion, after gelatin or Witte peptone, after colloidal silicate and 

 after starch injections the reactivity of the skin was markedly de- 

 pressed. Crystalloids did not alter the reactivity, in some instances 

 actually seemed to increase the reaction. Luithlen soon recognized 

 that this alteration had nothing to do with any commonly recognized 

 biological or antibody action on the part of the serum, but was due to 

 an alteration produced by practically every colloid injected. 



This change he considered dependent on an alteration in the per- 

 meability of the capillaries. In determining this change in permeabil- 

 ity he proceeded as follows: Rabbits were injected with Ringer's solu- 

 tion intraperitoneally (100 c.c.) and then 2 c.c. of a 10% solution of 

 sodium ferrocyanid was injected intravenously. The rate at which 

 the ferrocyanid permeated the Ringer's solution in the abdominal 

 cavity was then determined by adding hydrochloric acid and ferric 

 chlorid to samples drawn from the peritoneal fluid at various time 

 intervals and noting the time when the first blue coloration was ob- 

 tained. The normal time was about 2 minutes. Similarly the per- 

 meability to sodium iodid was determined and found to be about 

 1 minute. Variations were noted with the age of the animal and its 

 state of nutrition. 



When such animals were now injected with the various colloids 

 which had been found to depress the reactivity of the skin, it was 

 found that they all decreased the permeability of the capillaries as 

 measured in the manner that has been described. Salts did not alter 

 the rate of permeability very much, but repeated bleeding had a 

 definite effect on diminishing the permeability. 



Activation. If the reactivity of the skin can be altered in the 

 sense of a depression we must accept the corollary that nonspecific 

 factors may possibly be able to accelerate the cutaneous reaction. And 

 of this we have abundant evidence in the effect of thyroid feeding and 

 of iodid therapy to which Sherrick called attention some years ago 

 and which has been confirmed and amplified by a number of other 

 workers Kolmer, Sollmann, Stokes, etc. 



We are therefore led to the inevitable conclusion that elements 

 wholly nonspecific in our ordinary sense of immunological specificity 

 may be of decided importance in the mechanism of the skin reactions. 



Clinically, too, we have been forced to the same conclusion as a 

 result of observations on a variety of skin reactions which have been 



