264 BA CTERIOLOG Y. 



are of no pathological significance and have nothing 

 to do with the disease from which the individual 

 may be suffering. It is manifestly essential to ex- 

 clude these. It is not possible to exclude them cer- 

 tainly and completely under all circumstances, without 

 a more or less elaborate procedure ; but an effort to do 

 so should always be made. As a rule, the greater num- 

 ber of them may be removed from the skin by careful 

 washing with warm water and soap and a sterile brush, 

 after which the skin should be rinsed with alcohol and 

 allowed to dry spontaneously. The drop of blood may 

 then be obtained from the skin thus cleaned by a prick 

 with a sharp, sterilized lancet. The presence in the 

 cultures of a staphylococcus, growing slowly, with 

 white colonies, is a frequent experience, and does not 

 necessarily imply that this organism bears an etiological 

 relation to the disease from which the individual may 

 be suffering (see staphylococcus epidermidis albus, page 

 281). 



In the study of many of the common diseases, 

 notably the exanthemata, both at autopsy and during 

 life, by the methods above outlined, the investigation 

 often yields negative results, and yet there is every 

 reason for believing these diseases to be dependent for 

 their existence upon invasion of the body by some form 

 or another of living micro-organisms, capable of growth 

 in the tissues and susceptible of being transmitted from 

 individual to individual, either directly or indirectly. 

 In this connection it is appropriate to call attention 

 to the novel and important technical procedures that 

 have been employed by Nocard and Roux * in their 

 investigations conducted in the Pasteur Institute at 



1 Nocard and Roux : Annales de 1'Iustitut Pasteur, April 25, 1898. 



