44 THE HISTORY OF CREATIOISr. 



the number of phyla, or main groups, of the vegetable 

 kingdom may be reduced to the number of four. Mosses and 

 ferns may likewise be comprised as "Prothallus plants" 

 (Prothallophyta), and thereby the number of plant tribes 

 reduced to three — Flowering plants, Prothallus plants, and 

 Thallus plants. 



Very important facts in the anatomy and the history 

 of development, both in the animal and vegetable king- 

 doms, support the supposition that even these few main 

 classes or tribes are connected at their roots, that is, that 

 the lowest and most ancient primary forms of all three are 

 related by blood to one another. Nay, by a further examin- 

 ation we are obliged to go stiU a step further, and to agree 

 with Darwin's supposition, that even the two pedigrees of 

 the animal and vegetable kingdom are connected at their 

 lowest roots, -and that the lowest and most ancient animals 

 and plants are derived from a single common primary 

 creature. According to our view, this common primaeval 

 organism can have been nothing but a Moneron which took 

 its origin by spontaneous generation. 



In the mean time we shall at all events be acting cau- 

 tiously if we avoid this last step, and assume true blood 

 relationship only within each tribe, or phylum, where it has 

 been undeniably and surely established by facts in compara- 

 tive anatomy, ontogeny, and phylogeny. But we may here 

 point to the fact that two different fundamental forms of 

 genealogical hypothesis are possible, and that all the differ- 

 ent investigations of the Theory of Descent in relation to the 

 origin of organic groups of forms will, in futiire, tend 

 more and more in one or the other of these directions. The 

 unitary, or monophyletic, hypothesis of descent wiU endeavour 



