THE MICROSCOPE. 123 



An account was then given of the organisms found in splenic 

 fever, relapsing fever, chicken cholera, leprosy, etc., and the method 

 of Pasteur for the so-called attenuation of virus was described. 

 This method appears to depend largely on the exposure of the 

 broods of micro-organisms to the influence of oxygen; and recently 

 MM. Nocard and Mollereau have announced that the same can be 

 effected much more rapidly by the use of oxygenated water. The 

 question as to whether Pasteur's inoculation with artificially modi- 

 fied virus will afford permanent protection is still unsettled, for 

 sufficient time has not elapsed to decide it; but there is reason to 

 hope that it will be found to be of great practical benefit. 



The effects of microdemes in producing pyaemia and puerperal 

 fever are well described, and attributed to a poison secreted by 

 them, of the nature of the so-called ptomaines, rather than to their 

 mere mechanical presence. This knowledge is practically applied 

 in what is called antiseptic surgery; and the surgeon now under- 

 takes, without hesitation, operations which, twenty years ago, would 

 have been deemed quite unjustifiable; for he knows, that by insur- 

 ing that neither through the air nor the water, the sponges nor the 

 instruments, nor in any other way, a single microdeme which has 

 not had its powers of growth and reproduction totally destroyed 

 shall gain admission to the wound, he need have no fear of blood- 

 poisoning. 



As regards diphtheria, it is probable that it is due to a common 

 micro-organism, which, under circumstances not yet understood, 

 becomes virulent, as the micro-organisms of common sweet hay 

 infusion may be transformed into those which cause malignant 

 pustule. 



The connection of consumption with the microphyte is still 

 doubtful, though not improbable; and the same may be saicl with 

 regard to malaria. 



A sketch was then given of some of the characteristic phenom- 

 ena attending the great epidemics. For some, the germ theory 

 appears to afford the best explanation; for others, such as influenza 

 or cerebro-spinal fever, this theory is quite inadequate. 



Special attention was called to the many points in which our 

 knowledge of these subjects is still fragmentary and imperfect — 

 points which are to be settled by direct experiment. Such experi- 

 mental researches are of the highest value; and it is much to be 



