xi THE ELEMENTS OF STRUCTURE 195 



fern-seed," and even of the highest, for man himself has 

 to begin his life at the one-cell beginning. The fertilised 

 egg-cell divides and re-divides, its daughter-cells also 

 divide, the resultant units arc arranged in layers, woven 

 together to form tissues, compacted to form young 

 organs, and the result is such a multicellular body as we 

 possess ; but while this body-making proceeds, certain 

 units are kept apart, in some way insulated from the 

 process of development, to form the future reproductive 

 elements, which, freed from the adult body, will begin 

 a new generation. The contrast, then, is this, that the 

 Protozoa may be compared to the germ-cells of the 

 Metazoa ; while the daughter cells into which a Protozoon 

 divides separate from one another, the divided cells of 

 the fertilised ovum cohere to form a young animal. 



The gulf between the single-celled and many-celled 

 animals is a deep one, but it has been bridged. Otherwise 

 we should not exist. Traces of the bridge now remain 

 in what are called " colonial Protozoa," which, however 

 troublesome to those who like crisp distinctions, are most 

 instructive to those who would appreciate the continuity 

 of the tree of life. These exceptional Protozoa are loose 

 colonies of cells, daughter-cells of a parent unit, which 

 have remained persistently associated instead of going 

 free with the usual individualism of Protozoa. They 

 show us how the Metazoa or multicellular animals may 

 have arisen. 



3. Structural Analysis of the Body. The outer jorm 

 of normal animals seems to be always artistically har- 

 monious. There may be some ugliness in the lines and 

 colours of diseased animals, of domesticated animals 

 which man has exaggerated in some particular direction 

 such as fatness, of degenerate parasites which have 

 ceased to live an independent life, and of the unfinished 

 ante-natal stages of some animals, but beauty is the 

 rule. All free-living, finished, healthy animals in their 

 natural environment give us aesthetic pleasure, unless we 

 are unable to overcome prejudice against snakes, for 

 instance. Beauty is the stamp of a harmonious unity, 

 of a well-balanced individuality which has stood the test 



