Evolution in the Plant Kingdom. 328 
and Zoology are so mutually dependent and helpful that one can- 
not advance without the other, and the thoughts of both upon such 
a great question as evolution are practically the same. 
Turning aside, therefore, from the broad and much-travelled 
highway which leads from the Moners to Man, we will strike into 
a by-path, which extends from Protococcus to Phanerogam, and point 
out a few of its most salient features. Zoologists should be inter- 
ested in noting how the same ideas have been worked out in the 
into great kingdoms, and all should remark the wonderful unity: of 
purpose pervading the whole domain of life. 
I shall make no attempt to outline a great scheme into which 
every plant, however formed, shall fitly fall. If I were younger 
or less acquainted with botany, I could do this; for a young botan- 
ist usually begins by attempting to remodel all existing schemes of 
classification, just as a young college graduate can put veteran 
statesmen to shame. Botanists have no family-tree arrangement 
for plants, and will not attempt the construction of one until they 
know more about the life-histories of the lower groups and more 
about structure in all the groups. As Dr. Farlow said, in his Vice- 
Presidential address before the last meeting of the American Asso-. 
ciation for the Advancement of Science: “On abstract grounds 
alone, I presume that few botanists would object to the statement 
that all plants have developed from simple ancestral forms which 
were nearly related to some of the lower animals. But when it 
comes to saying in anything like a definite way that certain exist- 
ing forms have arisen from other lower existing forms or their imme- 
diate allies in some past epoch, and so on, until the lowest form is 
reached, botanists may well insist that imagination should not be 
allowed too large a scope in supplying missing links. It is precisely. 
in this point that zoologists have an advantage over botanists. The 
palzontological record of lower animals is more complete than that 
of lower plants, so that where the zoologist might reasonably form 
an hypothesis the botanist must rely more on his imagination, until 
ìn the end he finds himself in the possession of a chain composed, to a 
considerable extent, of missing links. As it is, if we would con- 
sider the evolution of plants, not getting much light on the pro- 
gress of the lower forms from paleontology, we are _ to 
trust largely to plants as we now find them, and to ask what are 
the inferences we are permitted to draw from existing structures 
and conditions,” : . 
