172 The Pehrine Corpuscles in the Silhworm. 



of a spider's foot, than to seek with Huxley for a community of 

 protoplasm between the finner whale and the fungus upon a fly. 

 The cilia3 of the vorticella and of the human bronchi are not 

 identical in structure, but they move in obedience to a similar 

 impulse. 



A medical friend once remarked to the writer of these pages, 

 that the periodical visitations and ravages of insects presented a 

 striking analogy to the recurrence and devastation of ej)idemic 

 diseases. It is well worth the investigation to inquire if they be 

 not ahke dependent upon similar hygrometric and thermometric 

 conditions of the soil and atmosphere. 



It is proposed here to point out the analogies which exist be- 

 tween the pebriue of the silkworm and syphihs in man, not because 

 these analogies might be so interpreted as to indicate that the two 

 disorders have, in common, a parasitic origin. It is because the 

 knowledge we at present possess relative to contagion is so scanty, 

 that it may be said every new observation of its phenomena 

 stimulates the belief that that which is UDknown and yet knowable 

 is largely in excess of that which is known regarding it. 



Bumstead, referring to this subject in a recent paper,* says : 



" The fact is, that a new field for investigation and experiment 

 has been opened, which no one has as yet fuUy explored, and no 

 one can pretend to understand. The exploration of this field 

 promises to throw light, not only upon syphilis, but upon other 

 contagious diseases, and even to add to our knowledge of the 

 nature of specific poisons in general ; but the work is yet undone, 

 and any conclusions at this time are only premature." 



It is preferable to select syphilis for the study of the analogies 

 referred to above, first, because it is a disease produced by a tangible 

 virus ; and, second, because of the multiformity of its results. It 

 is possible to secure upon the point of the lancet a drop of matter 

 which we can prove to be capable of producing all the complications 

 of the disease. This is also true of pebrine. While we have, 

 however, an equal opjDortunity of isolating the materies morhi in 

 vaccinia, variola, malignant pustule, and certain other maladies, the 

 polymorphism of the results produced is not equally marked as a 

 basis for comparison. 



It is, perhaps, proper to admit, at the outset, that the investi- 

 gations of Professors Strieker and Kobner have completely exploded 

 the theories of Lostorfer, Salisbury, and others, as to the existence 

 and causality of cryjyta syphilitica. We have no additional informa- 

 tion which would warrant us in reviving such dead issues. That 

 is not the purpose of this paper. It is here intended merely to 

 exhibit a general agreement between the origin and evolution of 

 two contagious diseases, existing in two widely-separated orders 

 * ' Am. Juur. of the Medical Sciences,' April, 1873. 



