78 PRIMITIVE FORMS OF LIFE 



variety of functions, and in intellectual manifestations. As 

 usual, a number of a priori ideas at first obscured the meaning of 

 the facts. Because our own personality has always been regarded 

 as an indivisible unit, and as indeed this word " individual ", 

 so often used to designate ourselves, has come to mean just 

 that — i.e. an indivisible personality — we experience some 

 difficulty in recognizing that this individuality was not achieved 

 at the first attempt, hence the resulting inevitable conclusions 

 meet with some resistance, even from people of distinguished 

 intelligence. Even if we admit that in the beginning things 

 might have happened otherwise, practically all organisms that 

 have passed the stage of the primitive living slime are to-day 

 constructed along similar lines and have attained their 

 definitive structure in the same way. We might add that the 

 exceptional cases that have been discovered, such as the Algse of 

 the Siphonese family, the Fungi of the Myxomycetes group, the 

 Infusoria of the genus Salinella of Semper, can all be easily 

 referred to the same general principles. 



The outstanding facts which we cannot possibly ignore may 

 be reduced to these four propositions : — 



i. Every organism, be it animal or vegetable, is formed by 

 the assemblage of elements, generally microscopic in size, 

 possessing a similar fundamental constitution, and known as 

 cells, anatomical elements, or, more recently, plastids. 



2. Some organisms exist that consist of but a single plastid, 

 and in nature to-day a multitude of forms, constituted by an 

 increasingly complex association of plastids, form a chain linking 

 together these isolated plastids, and the most complex organisms. 



3. Every living being starts from a single plastid, the egg, 

 and only attains its final complexity through repeated division 

 of the first plastid and those arising from it. 



4. The plastids that live as independent units divide as soon 

 as they have attained a certain size, in just the same way as 

 those destined to constitute organisms ; the only difference is 

 that the plastids resulting from this subdivision separate 

 from one another as soon as they are formed, whereas they 

 remain contiguous when they form part of an organism. 



This is equivalent to saying that the higher organisms 

 are exclusively formed by the gradual association of an 

 increasingly large number of plastids. Through this union they 

 unquestionably lose a certain amount of their independence, 



