244 THE BEGINNINGS OF II FE. 



I have also myself, quite recently, watched with the 

 greatest interest all the stages of this process, which 

 terminated in the evolution of fine specimens of 

 Parameciaj and am most pleased to be able to bear 

 my testimony to the general accuracy of M. Pouchet's 

 description. Up to this period I had never seen 

 a single Varamec'tum or other specimen of the larger 

 ciliated Infusoria in any of my hay infusions — these 

 having all been prepared either with warm or with hot 

 water. But about ten days previously, on re-reading 

 M. Pouchet's description of the mode of evolution of 

 these organisms, it struck me that I had failed to see 

 these phenomena owing to my never having made any 

 infusions with cold water. I therefore at once prepared 

 such a maceration, and two or three days afterwards 

 wrote to M. Pouchet on the subject. In the reply which 

 he was kind enough to address to me he said : — 

 'Jamais, jamais vous ne renconterez un seul infusoire 



cilie dans une experience faite a I'eau chaude II 



faut pour cela operer sur des macerations faites a froid ; 

 alors vous obtiendrez facilement la phenomene de 

 developpement des ceufs spontanes des Paramecies, dans 

 Jes membranes proligeres qui se seront formces d'abord^' 



On the evening of the day on which I received 

 this letter I again examined the thick pellicle which 

 had formed on the maceration of hay, and much to my 



^ M. Pouchet has been in the habit of using one part by weight of 

 ordinary dry hay to about forty parts of water, and of letting the mace- 

 ration stand for two or three hours before filtering off the clear liquid. 



