REGENERATION AND DEATH 213 



necessary to complete the new tail and the new head. 

 Through Professor Semper's kindness I had the 

 privilege of seeing many of his preparations, and can 

 therefore speak with confidence about his results. 



This completes the evidence which my time per- 

 mits me to lay before you in order to convince you 

 that the young type of cells really is physiologically 

 and functionally important, that it really does possess 

 the power of growth that I have attributed to it. 



We will pass now to another part of our subject, 

 with which the lecture will close. Age represents the 

 result of a progressive cytomorphosis. We have 

 learned that of cytomorphosis death is the end, the 

 culmination. It is a necessary result of the modifica- 

 tion and change of structure which goes on in every 

 individual of our species and of all the higher ani- 

 mals. We are familiar with the death of cells. It 

 occurs constantly and, as I have endeavoured to ex- 

 plain to you, it plays a great part in life. It promotes 

 the performance of various functions which are of 

 advantage to the body as a whole, which could not 

 be accomplished without the death of some cells. 

 But the death which we have in mind when we speak 

 ordinarily of death is something different from this. 

 It is the death of the whole. But even the death of 

 the whole has its strange complications. A great 

 deal of our knowledge of the functioning of the body 

 is due to the fact that the parts do not die when, as 

 we commonly say, the body as a whole, the indi- 

 vidual, is dead. The organ is alive and well. One 



