CX THE BEGINNINGS OF LIFE, 



and Florence, but of empires ; they decimate armies, disable 

 fleets ; they take the lives of criminals that justice has not 

 condemned; they redouble the dangers of crowded hospi- 

 tals ; they infest the habitations of the poor, and strike the 

 artizan in his strength down from comfort into helpless 

 poverty ; they carry away the infant from the mother's breast, 

 and the old man at the end of life ; but their direst eruptions 

 are excessively fatal to men in their prime and vigour of age. 

 They are emphatically the morbi popular es! 



No labour is too great, then, no pains should be spared, 

 in order to arrive at just conceptions concerning the origin, 

 nature, and mode of distribution of these scourges of huma- 

 nity. Deeply impressed with the difficulties surrounding 

 these great problems, and with the enormous importance of 

 strengthening the foundations of our knowledge in respect 

 to them, I was induced rather more than two years ago to 

 take up the investigation of some questions which lay at the 

 root of the whole subject. It seemed to me that no real 

 advance could take place in our power of controlling these 

 diseases until certain other great problems had been settled. 

 What is the real cause of fermentation and putrefaction? 

 Can the organisms which are associated with many of these 

 processes arise de novo? These were questions the solution 

 of which seemed to be of the utmost importance to the 

 science of medicine, as well as to the cause of science gene- 

 rally. Thus incited, I resolved to study such much-disputed 

 subjects for myself, with the view of arriving at some inde- 

 pendent opinion. 



As the results of this work have tended to strengthen 

 certain views concerning the epidemic and specific diseases, 

 and to make plain some points which were previously 

 involved in obscurity, I think I cannot do better than 

 attempt a somewhat hasty review of facts, which seem to 

 point conclusively to the necessity of entertaining opinions, 



