416 Royal Institution of Great Britain. 



A progressive tendency, according to the theory of evolution, marks 

 the organic series. The conversion of the " colony " into the " in- 

 dividual " (in other words, the concentration of originally separate 

 and independent " units " or " zooids ") is the chief developmental 

 cause of the differences between high and low organisms. The pri- 

 mitive condition of all organisms is the " colonial" condition. Egg- 

 segmentation (or, in Protozoa, body-division) is universal in the 

 animal world ; and cell- multiplication begins the development of 

 plant-life likewise. Arrest of development at an early stage dis- 

 tributes the separate units thus formed (as in Gregarina) ; arrest at 

 a later stage gives us the sponge colony (a series of similar aggre- 

 gated cells), or the tapeworm colony (a collection of essentially 

 similar " joints "). Physiologicallj', the higher organism devotes 

 less time to pure reproduction and becomes more explicitly busied 

 with individual interests. Hence the increased concentration of 

 energy which results in the formation of the highest " individuals," 

 that yet retain, in the " colonial " and cellular structure of their 

 tissues, the evidence of an originally compound nature. 



In the plant world, such " individualization " is seen as a secon- 

 dary tendency in the close aggregation of flowers in Compositae, 

 and in the transformation of uniform composites {e. g. thistle) into 

 individualized forms (e. g. daisy) through such intermediate steps as 

 the centauries. 



The conclusions of our study of " colonial " organisms are as 

 follows : — 1. The original condition of organisms is colonial : the 

 universal segmentation of the egg is a proof of this inference ; and 

 the development of new forms by this so-called process in low forms 

 like Gregarinse &c. supports this conclusion. 2. The lower we pro- 

 ceed in the scale of being, the more marked is the tendency to form 

 " colonial " organisms. 3. Arrest of development, by causing an 

 organism to cease progressing at a segregated stage, will tend to 

 produce a "compound" and "colonial" constitution. 4. The plant 

 world is " colonial " in its highest types. Plant- development has 

 not proceeded towards any marked increase of " individuality" over 

 the colonial nature of lower forms. A tree is in many respects as 

 markedly " colonial " as a Volvox. 5. The highest animals exhibit 

 lingering traces of an originally " colonial " nature in their histo- 

 logical composition. 6. The tendency of life-development is towards 

 concentration, and the conversion of the " colony " into the true 

 " individual." 



It is suggested by way of final inference, and by way of incursion 

 into a biological by-path, that the theory and idea of an originally 

 " colonial " constitution may explain the existence in man and higher 

 animals generally of those tribal and family associations which mark 

 the upper strata of existence. The semi-independent action of many 

 parts of the higher brain, for instance, receives an explanatory hint, 

 as to causation, from the idea of an originally independent and 

 colonial constitution. 



