44 THE HISTORY OF CREATION, 
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 still 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 primeval 
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 future, tend 
more and more in one or the other of these directions. The 
unitary,or monophyletic, hypothesis of descent will endeavour 
