212 THEORETICAL BIOLOGY 



panied by impoverishment in formative cells, and this we 

 must refer to the loss of genes. 



Through the loss of genes, the effect of the impulses, 

 which manifest themselves in the individual cells, becomes 

 more and more restricted and specialised, so that finally the 

 definitive cells of the full-grown organism retain in their 

 reserve-plasm, which does not enter into the framework, 

 nothing but the power to furnish that with special ceU-frame- 

 work in the event of injury. 



An exception to this rule is offered by the sex-cells, which 

 arise from the first divisions, and pass over into the sexual 

 organs of the adult unchanged and with all their genes. 

 I The phenomenon of the systematic loss of genes is as 



important to the course of development of the complete 

 animal as is the release of the genes, which likewise takes 

 place conformably with plan. Here also is to be seen an 

 invasion by the impulses according to plan, an invasion 

 belonging to the general melody which all the impulses obey. 



In many of the lower animals the loss of genes is not so 

 vj rigorously carried out as it is in the higher. This permits of 

 regeneration after extensive injury, to a much greater degree 

 than is possible among the higher animals. In the case of self- 

 mutilation especially, the cells, at least at certain places in 

 the body, must remain in possession of numerous genes in 

 order to make good the loss. 



POLAR SYSTEMS 



Thanks to the remarkable work of Braus, we are able 

 to get a clearer idea of the way in which the rule of genesis 

 affects shaping in space. 



If we cut away part of the homogeneous cell-material 

 from the germinal area that serves for the development of the 

 acetabulum, a socket is formed which is quite complete but 



