YELLOW FEVER. 427 



blood prior to its withdrawal from the body, was 

 probably correct. But it must be admitted that 

 the argument offered in favor of this view has no 

 great weight, and that the inference may be a 

 mistake. The fact that the fungus only appeared 

 occasionally in my culture-cells would be quite 

 easily reconciled with its somewhat abundant pres- 

 ence in the blood ; for an organism of this size 

 might be present in considerable numbers without 

 being found in every drop drawn from the finger. 

 But direct examination of very many specimens of 

 blood did not show it, whereas it is well known 

 that the spores of Penicittium are among the most 

 numerous of the organized particles suspended in 

 the atmosphere ; and their abundant presence in 

 the air of the Military Hospital of Havana was 

 demonstrated by aspiration experiments and mi- 

 croscopic examination. 



That portion of the Report of the Havana Com- 

 mission which relates to experiments on animals is 

 here quoted in full, as one of the objects which the 

 writer has had in view in the preparation of the 

 present volume has been to enable those who pro- 

 pose to enter upon experimental investigations 

 of this nature to readily avail themselves of the 

 experience gained by others who have preceded 

 them : 



Experiments upon Animals. 



" It has been commonly reported, and is asserted by 

 several writers of acknowledged ability, that during the 

 prevalence of yellow fever certain of the inferior ani- 



