TOXINS AND INFECTIONS 267 



but mitoses are rarely observed in the medullary cells follow- 

 ing such injuries. However, Graham 237 has reported active 

 regeneration of the medullary cells in a case of fatal "shock." 



EFFECT OF TOXIC AGENTS AFTER ADRENALECTOMY 



Adrenalectomized animals are not only hypersensitive to 

 such extraneous influences as excessive heat or cold, muscular 

 exhaustion, excitement, etc., as pointed out in Chapter VIII, 

 but they also show an abnormal sensitivity to various drugs 

 and toxic agents. This hypersensitivity has been demon- 

 strated for histamine, curare, strychnine, morphine, nicotine, 

 acetonitrile, adrenaline, diphtheria or tetanus toxins, cobra 

 venom, typhoid or staphylococcus vaccines, foreign proteins, 

 and other toxic agencies. In many cases this hypersensitivity 

 is very marked. 116 - U1 • 155 - 233 - 394 - 479 ' 629 



The increased sensitivity of adrenalectomized animals to 

 toxins will obviously depend upon the degree of adrenal insuf- 

 ficiency from which the animals are suffering at the time of the 

 injection of the toxin. Animals manifesting a marked degree 

 of insufficiency will succumb to doses which are only a fraction 

 of those tolerated by normal animals, while animals manifest- 

 ing only mild or no symptoms of insufficiency after an incom- 

 plete adrenalectomy will obviously not manifest an appreciable 

 hypersensitivity. This variability in the response of adrenalec- 

 tomized animals has led to the conflicting findings of different 

 investigators. Thus the reported normal resistance of adrenal- 

 ectomized rats to morphine or tetanus toxin is explained by the 

 fact that the animals were incompletely adrenalectomized (as 

 evidenced by their prolonged survival) and hence despite the 

 absence of macroscopically visible accessory tissue, were not 

 suffering from severe adrenal insufficiency. 



As first demonstrated by Dale and Laidlow, 148 adrenalectomy 

 greatly enhances the sensitivity of animals to histamine. It 

 is possible, however, that this hypersensitivity is in part (but 

 not completely as claimed by Wyman 691 ) attributable to the 



