THE BEGINNINGS OF LIFE. 193 



to give some account of the various changes that are 

 apt to occur in this aggregation of living units which 

 so soon collects, in the form of a scum, upon the surface 

 of nearly all infusions of organic matter. 



The pellicle is composed for the most part of a 

 dense aggregation of Bacteria of various sizes and 

 shapes imbedded in a more or less abundant, pellucid, 

 gelatinous material. Very frequently there are also a 

 variable number of intermixed Vlbrlones and more or 

 less characteristic Torufa 1 . The Bacteria in this layer 

 are mostly placed vertically to the surface, so that 

 an examination of the upper surface under the micro- 

 scope generally presents the appearance of a stratum 

 densely studded with small, though tolerably uniform 

 granules. On attempting to remove a portion of this 

 pellicle, it is found to constitute a more or less coherent 

 membrane. 



It is now a well-known fact that when two or 

 more Amoebae come into close contact with one an- 

 other, they may fuse so as to constitute a larger 

 individual of the same kind, which afterwards creeps 

 about and seizes food as its component parts had 

 previously done. Such a process must be classed under 

 the head of Homogenetic Biocrasis 2 , for, although 

 separate living units fuse to form a new individual, 

 the process is one of mere fusion, and the product 



1 The different kinds of 'pellicles' are more fully described by 

 M. Pouchet in his Het^rogenie,' pp. 355-367. 



2 See vol. i. p. 233. 



VOL. II. O 



