THE MONERON BECOMES A CELL. 345 
Only such homogeneous organisms as are yet not 
differentiated, and are similar to inorganic crystals in 
being homogeneously composed of one single substance, 
could arise by spontaneous generation, and could become the 
primeval parents of all other organisms. In their further 
development we have pointed out that the most important 
process is the formation of a kernel or nucleus in the simple 
little lump of albumen. We can conceive this to take place 
in a purely physical manner, by the condensation of the 
innermost central part of the albumen. The more solid 
central mass, which at first gradually shaded off into the 
peripheral plasma, becomes sharply separated from it, and 
thus forms an independent, round, albuminous corpuscle, 
the kernel; and by this process the Moneron becomes 
a cell. Now, it must have become evident from our 
previous chapters, that the further development of all 
other organisms out of such a cell presents no difficulty, for 
every animal and every plant, in the beginning of its indi- 
vidual life, is a simple cell. Man, as well as every other 
animal, is at first nothing but a simple egg-cell, a single 
lump of mucus, containing a kernel (p. 297, Fig. 5). 
In the same way as the kernel of the organic cell 
arose in the interior or central mass of the originally homo- 
geneous lump of plasma, by separation, so, too, the first cell- 
membrane was formed on its surface. This simple, but most 
important process, as has already been remarked, can like- 
wise be explained in a purely physical manner, either as a 
chemical deposit, or as a physical condensation in the upper- 
most stratum of the mass, or as a secretion. One of the first 
processes of adaptation effected by the Moneron originating 
by spontaneous generation must have been the condensation 
