50 THE HISTOEY OF CEEATION. 



another, or with the lowest animals on. the one hand, and 

 with the lowest plants on the other hand. It is not improb- 

 able that the classes specified, and many other unknown 

 classes of Protista, represent quite independent organic 

 tribes, or phyla, each of which has independently developed 

 from one, perhaps from various, Monera which have arisen by 

 spontaneous generation. If we do not agree to this poly- 

 phyletic hypothesis of descent, and prefer the monophyletic 

 hypothesis of the blood relationship of aU organisms, we 

 shall have to look upon the different classes of Protista as 

 the lower small offshoots of the root, springing from the same 

 simple Monera root, out of which arose the two mighty and 

 many -branched pedigTees of the animal kingdom on the one 

 hand, and of the vegetable kingdom on the other. (Com- 

 pare pp. 74, 75.) Before I enter into this difficult question 

 more accurately, it wiU be appropi'iate to premise something 

 further as to the contents of the classes of Protista given on 

 the next page, and their general natural history. 



It wiU perhaps seem strange that I should here again 

 l^egin with the remarkable Monera as the first class of 

 the Protista kingdom, as I of course look upon them as 

 the most ancient primary forms of all organisms without 

 .exception. Still, what are we otherwise to do with the still 

 living Monera 1 We know nothing of their palaeontological 

 ■origin, we know nothing of any of their relations to lower 

 animals or plants, and we know nothing of their possible 

 capability of developing into higher organisms. The simple 

 and homogeneous little lump of slime or mucus which consti- 

 tutes their entire body (Fig. 8) is the most ancient and 

 original form of animal as well as of vegetable plastids. 

 Hence it would evidently be just as arbitrary and unreason- 



