734 INFECTION AND IMMUNITY. 



that the intranuclear stage of the parasite does not 

 occur in vaccinia (Tyzzer), and we are led to believe 

 that this is an important differential point between 

 vaccinia and smallpox. Assuming that the bodies in 

 question cause the disease, the thought is pertinent that 

 the difference in virulence between vaccinia and variola 

 inoculata may depend on the failure of the intranuclear 

 cycle to appear in vaccinia. 



The work of Guarnieri, and particularly that of 

 Councilman, Magrath and Brinckerhoff, is most 

 suggestive, and ardent supporters of their views 

 have appeared with corroborative work (e. g., How- 

 ard). At the same time many skilled observers 

 discredit entirely the parasitic nature of the bodies 

 described, interpreting them rather as products 

 of degeneration of the epithelial cells and nuclei 

 or as inclusions of other tissue cells (e. g., leuco- 

 cytes, Borrel) or fragments of other nuclei. Swing 

 expresses similar views. The state of the question 

 is such that further study is urgently called for. 

 infection ^ Q have no positive knowledge as to infection 



Atrium. ... ,f ... 



atrium in smallpox, although the existence 01 a 

 "contagious zone" of atmosphere about the patient? 

 is good ground for the belief that invasion takes 

 place through the respiratory passages. The disease 

 which follows introduction of the virus into the 

 skin is spoken of as variola inoculata, and is much 

 less severe than smallpox. We are also ignorant to 

 a large degree of the means of excretion or dissem- 

 mination of the virus. Osier states that the virus 

 ina- "exists in the secretions and excretions and in the 

 exhalations from the lungs and skin." The dried 

 epithelial cells which are continuously thrown off 

 are no doubt a most important means of dissemina- 

 tion. Infection may be transmitted by means of 

 clothing or other materials which have been in con- 



