4 JOURNAL OF THE [January, 



For convenience in naming, we have been accustomed to con- 

 sider all material things as disposed upon distinctly separated 

 planes, placed one above another, like steps, thus marked off 

 into kingdoms (i) of the Elements, (2) of Chemical Compounds, 

 including Minerals, (3) of Plants, and (4) of Animals. In the 

 vegetable and animal kingdoms we have followed Linnaeus, in 

 regarding the inhabitants as gathered together in strictly bound- 

 ed groups of various degrees of importance, from sub-king- 

 doms down to species. And although this has been known as 

 the " natural system," it is now very plain that it is entirely ar- 

 tificial. The fact is that there are no clearly marked classes in 

 animate nature, but that what we choose to call kingdoms, 

 families, orders, genera, and species, shade off imperceptibly 

 into one another, in continuous succession, from the protoplasm- 

 speck upwards ; so that, instead of planes widely divided by 

 steps, and groups upon these planes rigidly fenced off from one 

 another, a gently sloping hill-side closely covered with every 

 possible form, — the simplest at the bottom, the most complex, or 

 most highly differentiated, at the top, — a perfect spectrum of the 

 whole living creation, displayed in gradually blending chromatic 

 bands from the base to the apex, and spreading laterally in infi- 

 nite variety of "combinations and interweavings, would probably 

 more nearly represent the system of Development as seen in the 

 light of the latest science. According to the present theory of 

 evolution, some such figure as I have just used would roughly 

 depict not only the relations of all material things as now exist- 

 ing, but also the relations of things as they have existed at any 

 one point of time in the past, or as they may possibly exist at 

 any period in the future. Moreover, it would in a general way 

 picture the relations of the whole succession of substances and 

 organisms from the beginning of time to the end. According to 

 this hypothesis, if we but knew just how to follow the clews, we 

 could trace a more or less irregular line from any one form to 

 any other we might select ; since it assumes a consistent and 

 continuous genealogical warp, underlying what at first sight ap- 

 pears to be a wholly incongruous pattern. 



It therefore results that, while we can point here and say these 

 are animals, and there and say those are plants, we cannot with 

 certainty indicate a line absolutely separating all animals from 

 all plants, or all animal characteristics from all plant character- 



