YELLOW FEVER. 423 



usually the glass slips were heated shortly before apply- 

 ing the covers, for the purpose of destroying any atmos- 

 pheric germs which might have lodged upon them. 

 These precautions were not, however, sufficient to pre- 

 vent the inoculation of certain specimens by germs 

 floating in the atmosphere (Penicillium spores and micro- 

 cocci) ; and in nearly every specimen the presence of 

 epithelial cells, and occasionally of a fibre of cotton or 

 linen, gave evidence that under the circumstances such 

 contamination was unavoidable. It is therefore believed 

 that any organism developing in the blood of yellow 

 fever, or of other diseases, collected by the method de- 

 scribed, or by any similar method, can have no great 

 significance unless it is found to develop as a rule (not 

 occasionally) in the blood of patients suffering from the 

 disease in question, and is proved by comparative tests 

 not to develop in the blood of healthy individuals, ob- 

 tained at the same time and by the same method. 



" Tried by this test it must be admitted that certain 

 fungi and groups of micrococci, shown in photographs 

 taken from specimens of yellow fever blood collected 

 at the military hospital and preserved in culture- 

 cells, cannot reasonably be supposed to be peculiar to 

 or to have any causal relation to this disease. While 

 we can claim no discoveries from the microscopic exam- 

 ination of the blood, bearing upon the etiology of yellow 

 fever, some interesting observations have been made 

 relating to the pathology of the blood in this disease. 



"It is not intended in this report to do anything more 

 than make a brief reference to these observations, as a 

 comparative study of the blood of other diseases will be 

 required to give value to them, and a detailed report 

 upon this subject is to be made at some future time. 

 The most important observation made relates to certain 

 granules in the white corpuscles shown in many of the 



