ACUTE INFECTIOUS DISEASES. 



sons vaccinated for the first time. 2. We should take this lymph, the 

 seventh or eighth day after vaccinating, from pocks which are perfectly 

 normal as regards size, form, and areola. The lymph from older or 

 younger pocks, or from those in any way abnormal, is less certain. 

 3. When possible, we should vaccinate from arm to arm. If obliged 

 to use old lymph, that which has been preserved in glass tubes, with 

 the ends sealed, is the best. 4. We should vaccinate through punc- 

 tures made with the lancet or vaccinating needle, and should choose a 

 part of the arm which would be covered even when short sleeves are 

 worn. About five punctures should be made in each arm ; sufficient 

 space should be left between the punctures to prevent the confluence 

 of the pocks or their areolae. 5. Except during the prevalence of a 

 small-pox epidemic, we should only vaccinate healthy persons. If the 

 vaccination do not succeed, we should repeat it after a few months. 

 6. When an epidemic of the disease breaks out, it is well to revaccinate 

 persons who have not been vaccinated for seven years or more. 7. We 

 should protect the pocks from pressure and friction, and should espe- 

 cially guard against children scratching their arms ; and we should 

 keep the patient in his room during the maturating fever. If there be 

 much inflammation around the point, we may apply compresses wet 

 with lead-water ; if ulcers remain, use cataplasms. 



CHAPTER VI. 



WIND-POX, WATER-POX, SHEEP-POX, VARICELLA, CHICKEN-POX. 



ETIOLOGY. Many dermatologists consider varicella as identical 

 with variola and varioloid, and as being the mildest form of small-pox. 

 From this view, the almost exclusive occurrence of this disease in 

 children is explained by saying that in them, from the short time which 

 has elapsed since vaccination, although the liability to small-pox is not 

 entirety gone, it is reduced to a minimum ; while in older persons tho 

 liability to small-pox is usually so much reestablished by the long pe- 

 riod that has elapsed since vaccination, that, when exposed to the con- 

 tagion, they are affected with varioloid. The falseness of this view 

 may be shown by striking examples. In the first place, the frequent 

 occurrence of varicella in children that have never been vaccinated, 

 speaks against the identity of varicella and variola poison. Why 

 should persons who might be supposed to have the greatest predispo- 

 sition to small-pox be so often attacked by the mildest form of the 

 disease ? But experience also shows that varicella offers no immunity 

 to vaccina or variola ; on the contrary, many children who have jusl 

 recovered from varicella are successfully vaccinated, or, during an eni 



