192 THEORETICAL BIOLOGY 



the properties of the definitive mosaic, since that can emerge 

 from it. The body-mosaic consists of cells which have very- 

 different material properties. It has been unanimously 

 assumed that in the germ there must be as many separate 

 rudiments as there are material differences in the macro- 

 mosaic. This seems to simplify things somewhat. For the 

 cells that are similar in material in the body-mosaic we hold 

 responsible a corresponding framework of rudiments of the 

 various substances, and this represents the micro-mosaic. 



This solution of the problem is open to objection. If we 

 try to picture the micro-framework in even quite a simple 

 case, such as the mosaic of a chess-board, we meet at once 

 with insuperable difficulties. Let us assume that within the 

 primordial stone there are only two separate rudiments for 

 black stones and for white ; it is very difficult to know 

 how to picture the rudiments of the 32 black and 32 white 

 stones, as well as their alternating positions in a square 

 field. 



If we are seeking for a material rudiment of the number 

 and arrangement of the stones, we are obliged to picture over 

 and over again a micro-framework exactly corresponding to 

 the final framework. It is not easy to see how this can really 

 make things simpler. 



The same holds good for all mosaics. Even the micro- 

 mosaic of a brick staircase, which need contain only one rudi- 

 ment for all the bricks, must reproduce their number and 

 their arrangement as steps, if it is to serve as the starting- 

 point for the finished structure. 

 V As I have already pointed out, Driesch's experiments have 



dealt the final blow to all speculations concerning a micro- 

 mosaic in the germ-cells, a mosaic which would have to be 

 vastly more complicated in the case of organisms than in 

 that of simple implements, such as the ones just cited. In the 

 germ-cells there is no micro-mosaic which could gradually 



