ON CELL FORMATION. 61 



-. Many masses of living matter are completely destitute 

 of any " cell wall " whatever. Portions may be seen to 

 project from the general mass for some distance, as if grow- 

 ing from it into the surrounding medium. These processes 

 often break off, and thus from one individual mass, many 

 separate masses may be formed. Each one of the resulting 

 portions grows and gives origin to new masses by division. 



No demonstration of the precipitation of living particles 

 from a clear fluid has yet been made by any one ; while, on 

 the other hand, it is easy to adduce examples in which the 

 origin of what appears to be an aggregation of living mole- 

 cules from a pre-existing living mass can be explained 

 most conclusively, but in a totally different manner. The 

 process can be watched quite distinctly in every stage in 

 various epithelial structures, and in the lower plants and 

 animals it may be actually observed to take place under the 

 eye of the observer. 



Professor Hughes Bennett in fact still supports the 

 old doctrine of the formation of cells by the aggregation of 

 particles precipitated from a fluid, and the subsequent for- 

 mation of a membrane around the collection. He attributes 

 the formation of tissues to molecules : " The first step in 

 the process of organic formation is the production of an 

 organic fluid; the second, the precipitation in it of organic 

 molecules, from which, according to the molecular law of 

 growth, all other textures are derived either directly or in- 

 directly." Low organisms are supposed to be formed by 

 the coming together and adhesion of particles precipitated 

 from a fluid. But these doctrines concerning the formation 

 of cells, though still taught, do not accord with the facts that 

 can be demonstrated by the student himself in the growth 



