THE BEGINNINGS OF LIFE. 229 



have nearly attained their full size, are still (although 

 units exhibiting a distinct vitality of their own) mere 

 structureless bits of protoplasm, without cell-wall and 

 without nucleus differing, in fact, in no respect from 

 the Vrotamceb-e of Professor Haeckel, except that they 

 are subordinate parts of a higher organism, and there- 

 fore do not lead an entirely independent existence. 

 It seems evident also that such homogeneous masses 

 of matter (plastides), already exhibiting vital character- 

 istics, are afterwards capable of evolving a nucleus, and 

 of assuming that cellular form without which it was 

 formerly supposed no vital manifestations could occur. 



Such a mode of origination of living units, together 

 with their subsequent evolution, affords perhaps the 

 best illustration that can be given of the birth of 

 cells de no<vo in blastemata. Other evidence of vari- 

 ous kinds can however be adduced tending towards 

 the same conclusion, and to this we will now briefly 

 allude. When working at the anatomy of a diseased 

 spinal cord in the year 1866, before my faith in 

 Virchow's doctrines had been notably shaken, I was 

 much struck by certain appearances met with through- 

 out the degenerated portions of a cord in which the 

 interstitial fibrous tissue had become abnormally in- 

 creased in quantity. As in such tissue generally, there 

 was a very great increase in the number of nuclei, and 

 although very many of them appeared about ^jVzr" in 

 diameter, there were others even larger than this, and 

 others still in great abundance representing every 



