189O.J NEW-YORK MICROSCOPICAL SOCIETY. 41 



covered that even in the healthy animal system alkaloids were 

 being constantly compounded, which could not be clearly dis- 

 tinguished from the vegetable alkaloids, or ptomaines. For these 

 the name leucomaines was invented. But, having found that 

 ptomaines were always products of fermentation, it was a natural 

 step to the assumption that leucomaines must be results of 

 a like process ; and good reasons quickly appeared for this gen- 

 eralization. Fermentation, during which ptomaines are pro- 

 duced, being a phenomenon of nutrition, as between a uni- 

 cellular organism and its pabulum : the organism, the ferment, 

 being introduced from without into the fermentable substance ; — 

 analogy easily led to the conclusion that the production of leu- 

 comaines is a phenomenon of nutrition as between the normal 

 constituent element of the body — (whether the old-fashioned 

 cell, or the new-fashioned protoplasmic reticulum), — and its 

 nourishing fluid. 



Professor Joseph LeConte has recently called attention to this 

 latest tendency of the cell doctrine, on which subject he says : 

 " We have seen that ptomaines are alkaloids of albuminoid de- 

 composition generated in the presence and under the guidance 

 of microbian life. Now there is going on continually in the 

 animal body, as a strictly physiological process, albuminoid de- 

 composition (wasting of the tissues) in the presence and under 

 the guidance of cell life. This also, as might be expected, pro- 

 duces poisonous products * * * * If they are not also usually 

 deadly to the animal body, it is only because they are continu- 

 ally being eliminated by appropriate organs." ^^ And this 

 elimination, we may well imagine, is a result of the operation of 

 natural selection, which has not yet |)roduced immunity against 

 all ptomaines, as it has against most leucomaines. 



As it is not my purpose to discuss the germ theory itself, I 

 shall not follow this subject further. Sufficient has been said to 

 indicate the direction in which the cell doctrine, or perhaps I 

 should say the protoplasm theory, is once more moving. 



I must therefore bring my already too lengthy sketch to an 

 end although, before actually closing, I cannot refrain from sum- 

 marizing some of the conclusions which seem to me to be justi- 

 fied by the historical survey which I have endeavored to make. 

 First, then, the original idea of the cell, as propounded by 



»=> Letter to " Science." Nov. 8, 1889, 



