

The Beomnmg- and End of Life 397 



e reproduced in the last-named animals. The legs and 

 claws of lobsters will similarly grow again if removed at 

 one of their joints. If certain worms be cut in two, each 

 half will become a perfect animal, the head producing a 

 new tail and the tail a new head, and a worm of the genus 

 Nais has been cut into as many as twenty-live parts with 

 a like result. 



In higher animals, artificially separated parts often con- 

 inue for a time to exhibit a certain vitality. A tadpole's 

 tail will, for a short period, continue to grow, and a separate 

 lizard's tail will also move rapidly. Frogs' amputated legs 

 long continue to respond to stimuli. The heart will con- 

 tinue to beat on removal from the body, and after death 

 the various tissues of the bodily frame continue for different 

 extents of time to show signs of vitality. The animal which 

 is perhaps the most remarkable for its power of repairing 

 injuries is the Hydra, almost any fragment of which will, 

 under favourable circumstances, grow into a new and entire 

 animal. The sea-anemone {Actinia) has also very great 

 power of the same kind. This process, which excites our 

 surprise and admiration in the case of animals, is so familiar 

 to us in plants, that no one thinks the formation of new 

 individuals by ' cuttings ' a matter of wonder. Certain buds 

 also of some plants, notably tiger lilies, Avill detach them- 

 selves, and develop into plants like those which bore them. 



We must confess that Professor Weismann's theory does 

 not appear to us to harmonise with such facts as these. He 

 attempts to explain them by affirming that the germ-plasm 

 must be present in all such parts of divided or injured 

 organisms. But it hardly seems credible that this hypo- 

 thetical substance can be so distributed through the body 

 that each part or organ should have just that portion of 

 it needed to bring about its own repair when injured. As 

 to the difference between the germ-plasm of the embrya 



