1897] FUNDAMENTAL PRINCIPLES OF HEREDITY 239 



Reviewing the facts, we find that 



(i.) In Protista, each cell retains the power of reproducing in 

 its offspring its own characters or those of a direct ancestral cell, 

 which we may term the law of direct cellular transmission 

 uninterrupted or alternating, according as only one or several 

 alternating modes of cellular reproduction constitute the genetic 

 cycle. 



(ii.) In Metazoa, the power of reproducing a complete organism 

 is confined to certain reproductive cells, which must beget in their 

 progeny cells like those which are only related to them collaterally ; 

 this we call the law of collateral cellular transmission. 



(iii.) The remaining cells of the Metazoan can seldom or never 

 revert closely enough to a primitive type to produce all those other 

 tissues of which they are collaterals, though their propagative power 

 may be very great. This limitation of reproductive power we may 

 call the law of specialised sterility. 



(iv.) In most cases of animal budding or repair we find that the 

 several tissues co-operate to produce a complete organism ; this we 

 call the law of co-operative propagation. 



Marcus Hartog. 



(To be continued.) 



