7o6 LIFE : OUTLINES OF GENERAL BIOLOGY 



part around the nucleus, and extending from this in opposite direc- 

 tions the fibre-like portions with the power of contraction. Striped 

 or skeletal muscle, again, is still more highly specialised; the fibres 

 may be over an inch long and angular in section; close to the 

 surface may be seen the nuclei, of which there may be even many 

 hundreds in a single fibre, though each fibre behaves as a single 

 cell. In the connective tissues, which include bone, cartilage, and 

 fat, there is usually a light scaffolding of straggling cells and a 

 non-living ground substance of very variable nature, according to 

 the particular kind of tissue. 



TAXONOMIC 

 THE PROBLEM OF SPECIES 



Not only herbalists and zoologists, but ordinary observers, to thi- 

 day, recognise plants and animals "according to their kinds" 

 witness oak and mistletoe, rook and robin, each of which there is no 

 mistaking; and also other plants and animals without number, as 

 observation goes on ; hence, it seems that, like Adam of old, we can 

 name all manner of creatures. Yet as we come to know more and 

 more of them, and look at them more closely, trouble begins. An 

 our big oak-trees all of one kind? So it at first seemed, even t( 

 woodman and carpenter; yet the simple villager, seeking the best 

 acorn-forage for his swine in autumn, may well have noticed that 

 some trees bear their acorns on stalks, while others have them 

 seated close on the branch. If so, he thus anticipated Quercus 

 robur, var. pediincidata and var. sessiliflora of Linnaeus, who, as our 

 modern Adam, in such ways advanced the naming of species, and 

 varieties, to a new clearness; and with acceptance accordingly in 

 the main, and almost without question, until the coming in of 

 evolution doctrines. Indeed, practically to this day; for though 

 we no longer accept his conception of species, as in direct descent 

 from those originally created, we still in our way hold that 

 descent doctrine, though now extended from variety to species, to 

 genus, and to larger and larger groups again. Indeed, in a way, wc 

 conserve his conception of varieties too, though now so vastly 

 stretching it out; since all the species of a great genus and moii 

 have for us arisen as varieties of some far-back species; all moK 

 or less preserving their fundamental likeness, yet increasingly 

 accenting and accumulating their variations too, until these may 

 even be so great as to conceal their likeness not a little. Indeed, 

 Linnajus, for all his strictness, was coming to a pretty clear notion 

 of this, in fact was on the way to becoming an evolutionist; for he 

 at length saw that many of his "distinct species" of a large genu^ 



