THE BEGINNINGS OF LlfE. 373 



more specialized and more sensitive. The epithelial 

 layer is dependent for its life upon the continuance of 

 a set of conditions which are only possible so long as it 

 constitutes an integral part of a living organism. Soon 

 after the death of the human being of which it formed 

 part, the interference with, and ultimate arrest of, the 

 conditions under which the epithelial layer was fitted 

 to live, entails a gradual arrest of those molecular 

 actions which made up the life of its several parts. The 

 Alga, however, being an independent organism, is 

 amenable only to more general conditions, and, during 

 its periods of molecular re-arrangement, it continues 

 to exist in the fluid medium in which it has been born. 

 But, for the morphological units of each alike for 

 the epithelial cell, and for the algoid cell or compart- 

 ment we are warranted in claiming a kind of organi- 

 zation. They, as simplest morphological units, are 

 themselves organisms compounded of living molecules. 

 And, just as we have seen that the death of an or- 

 ganism, as a whole, does not entail the death of its 

 several parts, unless it happens that such death of the 

 whole organism brings about, as a necessary conse- 

 quence, a cessation of those conditions under which 

 alone the several parts are fitted to exist; so does it 

 seem reasonable for us to imagine that the conditions 

 under which certain of these simpler organisms exist 

 may be such as to enable their life to persist under 

 other forms, when a continuance of the form previously 

 in existence becomes no longer possible. The complex 



