260 On the Mycelium of Smallpox of Sheep. [June 15^ 



preparations of tissues* altogether removed from the suspicion of con- 

 taining fungoid growths of that or any other character. 



A comparison of the two kinds of specimens convinced me that the 

 appearances represented in my figures 18 and 19 are not due, as I sup- 

 posed, to a mycelium in the cavities of the primary pustules, but are 

 products of coagulation of some albuminous or kindred material by the 

 reagent that had been employed for hardening the object in question 

 (dilute chromic acid and spirit). 



The vegetable nature of the other structures — viz, those represented in 

 figs. 9, 10, and 11 (^. e. the supposed mycelium in the lymphatics of the 

 skin of the pock) as well as those in figs. 16 and 17 {i.e. the mycelium in 

 the cavities of the secondary pustules) — becomes therefore very doubtful. 

 My doubt as to these being also produced by coagulation is based partly 

 on the similarity between the last-named features and those undoubtedly 

 non-vegetable objects in Dr. Creighton's specimens and also in my figures 

 18 and 19, and partly on the following circumstances: — (1) I have lately 

 ascertained that blood, especially in febrile conditions, which is contained 

 in blood-vessels of tissues that had been subjected, in a fresh condition, to 

 the hardening fluid {e. g. chromic acid) presents appearances very similar to 

 branched mycelium-threads to which are attached numerous conidia ; the 

 presence of more or less unaltered blood-corpuscles proves their true cha- 

 ractert. (2) I have likewise seen that blood-plasma containing globulin or 

 parts of blood-corpuscles, when in lymphatic vessels or kindred spaces, show 

 sometimes in the course of coagulation similar appearances. Whether the 

 greater number of the thread-like structures is due to fibrin or to blood- 

 corpuscles I cannot determine as yet ; but it seems to me that both is the 

 case. 



In the case of Variola ovina it is therefore probable that the supposed 

 mycelium in the lymphatics is due to coagulation of some substance 

 directly connected with blood. "Whether the appearances in the cavities 

 of the pustules, however, owe their origin to the same or to certain mu- 

 cous substances, as appears in Dr. Creighton's specimens, and under 

 what conditions these substances present the fungus-like characters, is a 

 subject which I intend to investigate more fully. 



* Sections through hardened mammary glands. 



t Blood-corpuscles, or only portions of them, become fused so as to form longer or 

 shorter thread-like structures, to which are attached smaller or larger particles of 

 blood-corpuscles. 



