8 REPORT — 1879. 



others locomotion is effected by means of cilia — microscopic vibratible* 

 hairs, which are distributed in various ways over the surface, and which,, 

 like the pseudopodia and flagella, are simple prolongations of their pro- 

 toplasm. 



In every one of these cases the entire body has the morphological 

 value of a cell, and in this simple cell reside the whole of the properties 

 which manifest themselves in the vital phenomena of the organism. 



The part fulfilled by these simple unicellular beings in the economy 

 of nature has at all times been very great, and many geological forma- 

 tions, largely built up of their calcareous or silicious skeletons, bear 

 testimony to the multitudes in which they must have swarmed in the 

 waters of the ancient earth. 



Those which have thus come down to us from ancient times owe their 

 preservation to the presence of the hard persistent structures secreted by 

 their protoplasm, and must, after all, have formed but a very small propor- 

 tion of the unicellular organisms which peopled the ancient world, and 

 there fulfilled the duties allotted to them in nature, but whose soft, perish- 

 able bodies have left no trace behind. 



In our own days similar unicellular organisms are at work, taking 

 their part silently and unobtrusively in the great scheme of creation, and 

 mostly destined, like their predecessors, to leave behind them no record 

 of their existence. The Red Snow Plant, to which is mainly due the 

 beautiful phenomenon by which tracts of Arctic and Alpine snow become 

 tinged of a delicate crimson, is a microscopic organism whose whole body 

 consists of a simple spherical cell. In the protoplasm of this little cell 

 must reside all the essential attributes of life ; it must grow by the 

 reception of nutriment ; it must repeat by multiplication that form 

 which it has itself inherited from its parent ; it must be able to respond 

 to the stimulus of the physical conditions by which it is surrounded. 

 And there it is, with its structure almost on the bounds of extremest 

 simplification, taking its allotted part in the economy of nature, com- 

 bining into living matter the lifeless elements which lie around it,, 

 redeeming from sterility the regions of never- thawing ice, and peopling 

 with its countless millions the wastes of the snow land. 3 



But organisation does not long rest on this low stage of unicellular 

 simplicity, for as we pass from these lowest forms into higher, we find 

 cell added to cell, until many millions of such units become associated 

 in a single organism, where each cell, or each group of cells, has its 

 own special work, while all combine for the welfare and unity of the 

 whole. 



In the most complex animals, however, even in man himself, the com- 

 ponent cells, notwithstanding their frequent modification and the usual 



3 The Red Snow Plant (Protocoecus nivalis) acts on the atmosphere through 

 the agency of chlorophyll, like the ordinary green plants. As in these, chlorophyll 

 is developed in it, and is only withdrawn from view by the predominant red pig- 

 ment to which the Protocoecus owes one of its most striking characteristics. 



