96 Thomas Henry Huxley 



of these map pieces. The iiltiinate picture was the 

 conception of the whole world of life, past and present, 

 as a single famil}^ tree growing up from the simplest 

 possible roots, and gradually spreading out first into 

 the two main branches of animals and plants, and then 

 into the endless series of complicated ramifications 

 that make up livnng and extinct animals and plants. 

 Huxley was piecing together the scattered fragments, 

 and gradually learning to see here and there whole 

 branches, as yet separate at their lower ends, but in 

 themselves shapely, and showing a general resemblance 

 to one another in the gradual progression from simple 

 to complex. The greatest of these branches that he 

 had pieced together was the group of Medusae and 

 their allies, now known as Coelenterates. He had 

 formed similar branches for the Molluscs and minor 

 branches for the Salps and Ascidians, and, in his gen- 

 eral lectures on the whole animal kingdom, he had 

 shadowed out the broad arrangement of the main divi- 

 sions, or, as he called them, .types. He had seen in each 

 particular branch the clearest evidence of the laws of 

 growth which had directed its development, and had 

 realised that these laws of growth, consisting of gradual 

 modifications of common typical structures, were identi- 

 cal in the different branches. He had taken clear hold 

 of Von Baer's conception that the younger stages of 

 different types were more alike than the adult stages, 

 and here and there he had made comparisons between 

 the younger stages or simplest forms of his different 

 branches, and had shown that, without completely 

 realising it, he was ready for the idea that just as the 

 separate pieces could be arranged to form orderly 

 branches, so the separate branches might come to be 

 arranged as a single tree. And finally, in his lectures 



