18 The Philippine Journal of Science 1913 



II. EXPLANATION OF BASIC FACTS 



We can think of two possible, complete, and satisfactory 

 explanations for the above facts. 



1. Thfe germ of smallpox by passage through certain lower 

 animals loses (acquires) certain properties, and it transmits 

 its altered condition to its offspring forever, a more striking 

 instance of hereditary transmission of acquired characteristics 

 than has ever before (so far as we know) been cited. 



2. Smallpox is due to a dual and divisible virus, one part of 

 which causes vaccinia and the specific smallpox eruption, the 

 other part being necessary for the production of the contagious, 

 generalized, mortal disease tvith a distinct preemptive stage 

 and initial rashes. 



We are unable to imagine a third explanation - that does not 

 ignore facts now known ; of the two set forth above we favor the 

 second for two reasons : 



A. Without desiring to enter into the discussion of the hered- 

 itary transmission of acquired characteristics and without 

 professing to have made a thorough study of the subject, we 



' Kelsch and his coworkers*^' appai-ently hold the view that variola 

 virus and vaccinia virus are distinct entities, but are derived from a 

 common stem. This view ignores, and Kelsch appears to deny, the pos- 

 sibility of transformation of smallpox to vaccinia by animal passages, a 

 fact that we consider clearly established. 



Meirelles(^) advances the view that smallpox is flea-borne and argues 

 at length in favor of his belief. Under this hypothesis it would be under- 

 standable that the smallpox virus undergoes a sexual stage of development 

 in the flea and that vaccinia is milder because it lacks that stage. But 

 we think this disproved by several facts; namely: 



1. Inoculated smallpox never changes in man to vaccinia. C^' 



2. Variola may be transmitted to man after 3 or even more animal 

 passages that have all been made by inoculation. 



3. Vaccinia has never been known to start a smallpox epidemic, even 

 in Meirelles' own flea-ridden country. 



4. Strains of vaccine have been kept pure as such, by human passages, 

 since Jenner's day, probably too long a period for an asexual phase of a 

 normally sexual organism to live. 



Supfle<^) says that the vaccine germ remains localized and only leads 

 to a local manifestation and reproduction. The immunity is purely histo- 

 genic and is limited to the epithelial layers that are physiologically closely 

 related to the inoculation site. The nature of the attenuation of variola 

 to vaccine lies in the fact that the growth intensity of the germ is lowered 

 by calf passage. The immune bodies are developed and appear soon enough 

 to prevent generalization of the locally inserted vaccine germs. This hypo- 

 thesis ignores the fact that vaccinia never regains the power to produce 

 smallpox, even though it become generalized at times. 



