THE BEGINNINGS OF LIFE. 



The corpuscles gradually moved more briskly j and finally, 

 detaching themselves altogether from the pellicle, they 

 became free-swimming animalcules each of which had 

 a rapidly vibrating flagellum. Their development fre- 

 quently took place in groups of various sizes, as above 

 described j but when the solution contained less organic 

 matter, or when the weather was colder, single isolated 

 corpuscles were frequently seen developing in different 

 parts of the pellicle. 



The description given by M. Pouchet of the mode 



*:; 



FIG. 52. 

 Origin of Monas lens. (Pouchet.) ( X 1800.) 



a. First Stage. c. Corpuscles with motionless tails. 



b. Tailless Corpuscles. d. Fully-developed Monads. 



of evolution of Monas lens is essentially similar. He 

 observed the first rudiments of them in the pellicle of 



