THE BEGINNINGS OF LIFE. 165 



various Algae, or, as Cohn ascertained by his obser- 

 vations upon Protococcus fluvialis, they may from time 

 to time give birth to many more actively moving, 

 animalized forms belonging to the group Monadima. 

 So that as Cohn remarks, after summarizing the re- 

 sults of his observations upon the actual develop- 

 mental forms assumed by Protococcus 1 : c A critical and 

 comparative consideration of the foregoing facts would 

 therefore appear to render untenable almost all the 

 principles which modern systematists have hitherto 

 adopted as the basis for construction of their Natural 

 Kingdoms, Families, Genera, and Species.' 



Views' of the kind hitherto announced, startling as 

 they may appear, had previously found favour in the 

 eyes of many philosophic naturalists. And however 

 much such doctrines may have been confirmed and 

 placed upon a more secure basis by recent researches 

 and observations, we may admire the breadth of view 

 and scientific prescience which revealed themselves 

 when the following views were expressed by my respected 

 friend and colleague, Professor Grant, in c Lectures on 

 Comparative Anatomy' published in i833 2 . In many, 

 though of course not in all respects, they closely repre- 

 sent our present state of knowledge on the subjects to 

 which they refer. He said : 



1 For an enumeration of these surprising metamorphoses, see Ap- 

 pendix D, p. Ixxxii. 



2 In ' Lancet,' vol. ii. p. 1001. 



