258 Dynamic Theory. 



has had varioloid never has the small-pox thereafter, but if a person not protected (as by 

 vaccination ) be exposed to the contagion of varioloid, however mild it be, he is in the 

 same danger of regular small-pox as he would be from exposure to small-pox itself. So 

 that the disease is different only as the condition of the victims is different. As is well 

 known both sorts of small-pox are extremely contagious and portable by means of cloth- 

 ing or otherwise. The epidermic excreta of this disease, as well as those thrown out of 

 the system by the breath, are carried into the air and set up the disease in others by be- 

 ing swallowed or taken into the mouth, and then penetrating to the blood through an 

 epthelium or mucous membrane. It is remarkable that the disease taken in this the 

 natural way should be so much more severe and fatal than when taken by inoculation. 

 Taken in the natural way the mortality is from 10 to 33 per cent. Small-pox prevents its 

 own return, as a general rule. It is accompanied by the round bacteria, or micrococci, 

 which are found in blood vessels of the skin, and sometimes in the blood vessels of the 

 liver, spleen, lymphatic glands and kidneys. 



Vaccinia, or cow-pox, is a disease of cattle, which bears some resem- 

 blance to the human small-pox. The lymph of cow-pox contains micrococci, which are 

 similar to, if not identical with, those in the lymph from the small-pox vesicles. Cow- 

 pox is transferable to the horse, in which animal it is called grease. It appears in the 

 horse as an inflammation affecting the skin of the heels. Inoculation with matter from 

 the grease produces in man the disease called grease-pox ( variola equinse ) which, in 

 the prevention of small-pox, has precisely the same effect as cow-pox. There is also an 

 epizootic, or contagious disease, called murr, which affects sheep the French call it 

 clavelee which is analagous to, if not identical with, cow-pox. Cow-pox is contagious 

 among cattle, spreading rapidly at times through several herds, at other times spreading 

 slowly. It is not dangerous ; fatal cases being extremely rare. Men have caught the dis- 

 ease from cows while milking them. I should suppose the milk of diseased cows would 

 communicate it, but have no authority for it. This disease is so nearly like small-pox 

 that it prevents small-pox in the same way in which that disease is a bar against its own 

 return. However, its influence wears out and inoculation must be repeated after a term 

 of years variously stated from three to twenty. Cows may be inoculated with human 

 small-pox and be affected by the symptoms of cow-pox only. But vaccination of a hu- 

 man subject by virus from such cow-pox may communicate the disease of genuine small- 

 pox. Vaccination is almost as effectual against a recurrence of small-pox as small-pox 

 itself. And when it does return after either, it is in the form of the comparatively mild 

 varioloid. It is not settled what constitutes the contagium of these diseases. " The ex- 

 periments of Chauveau have rendered it probable that the contagium is a molecular 

 .substance, and is not dissolved in the lymph." (Flint.) I think the facts warrant the 

 conclusion that all these diseases have had a common origin, and have received slight 

 modifications from long habit in slightly differing environments ; and that they are due 

 to either an organic or soluble ferment, or both together. 



Varicella or chicken-pox. This is another eruptive disease which 

 prevails chiefly among children, but sometimes is experienced by adults. It is conta- 

 gious among children, but seldom so with adults. It is characterized by the formation 

 of small vesicles on the skin filled with a liquid, which finally dry up without leaving pits. 

 The symptoms so much resemble those of varioloid as to lead often to erroneous diag- 

 nosis. But it is not known to develop into variola or varioloid, and may prevail in the 

 absence of either. It is no protection against either of the other diseases. Where the 

 miasm is originally generated, or what causes it, is not known ; but it is contagious and 

 sometimes epidemic. It is comparatively harmless and cures of itself if let alone. 



Scarletina or Scarlet fever is a contagious eruptive disease more com- 

 mon in children three or four years old than in adults. As a rule it is only experienced 

 once. It is accompanied by high fever, scarlet redness, and eruptions of the skin, vio- 

 lent inflammation of the jaws and pharynx, often extending along the eustachian tube 

 into the drum of the ear, and is followed by desquamation or a peeling off of the epider- 

 mis. The contagium of this disease is contained in the exhalations of the breath, and 

 those from the skin, thrown into the air, and are often carried in the clothes of attendants 

 for long distances, and infected garments, furniture, &c., may be able to communicate 

 the disease long after they receive the contagium. The disease often follows surgical 

 operations. No vital organism has been observed in connection with scarletina. 



Another eruptive, contagious disease is the well known Measles or 

 Rubeola. It is often of an epidemic nature. It is portable, being carried from one place 

 to another by persons who have been near it. It is in general characterized by fever, 

 watery eyes, serous discharges from the mucous membrane of the nose cavities and ad- 



