426 THE BEGINNINGS OF LIFE. 



Thus several reasons are discoverable why the changes 

 taking place in the matter of aquatic organisms 

 should give rise to much more varied and also to much 

 higher metamorphic products than those commonly de- 

 rived from the c pellicle.' The developmental phases 

 here encountered are indeed very comparable with 

 some of those which have been already described in 

 Appendix D as definite changes in the life-history 

 of many of the lower forms of life. And what has 

 since been made known does much to strengthen 

 the supposition then advanced 1 . Instead of looking 

 upon many of these sets of changes as definite series 

 which were always likely to occur in the same order 

 when similar organisms were observed at different times, 

 it was suggested that the existing testimony of skilled 

 observers, not only pointed to the conclusion that 

 no such regularity was observable, but also rather 

 tended to favour the supposition that we had to do 

 merely with a living matter which far outdoing the 

 fabled Proteus was capable of ass'uming an almost 

 endless diversity of living forms, under the influence of 

 varying changes in its own substance, and various 

 modifications in the nature of its environment 2 . Before 



prendre des colorations vertes, violettes, ou bleues. . . . C'est la le fait 

 important qui me parait dominer ce travail, et qui pourra servir <i expli- 

 quer les differentes teintes qu'offre la chlorophylle dans la vegetation.' 



1 This Appendix was written two years ago, when I was unaware of 

 the possible occurrence of many of the heterogenetic transformations 

 which have now been recorded. 



2 See Appendix D, pp. xcvii. and Ixxxiii. 



