MODERN BIOLOGY 607 



essential difference between animate and inanimate very quickly lose ail ap- 

 preciation of what is truly characteristic in living matter and its metabolistic 

 phenomena, which must otherwise be the chief interest even of those bi- 

 ologists who maintain the old assertion, already proclaimed by Kant, that 

 only material phenomena can be subjects for natural-scientific treatment. It 

 is not, then, the idea — in itself justifiable — of limiting discussion to the 

 chemical and physical manifestations of the phenomena of life that consti- 

 tutes the weakness of these mechanistic theories of life, but the stubborn 

 insistence upon the rough comparisons between phenomena in animate and 

 inanimate nature — comparisons, in fact, the weakness of which would un- 

 doubtedly be realized by their proponents if the latter were not really trying 

 all the time to lay the foundations of some kind of general philosophical 

 theory extending far beyond the bounds of natural science. When Verworn 

 discusses and denies the possibility of the immortality of the soul, he is 

 arguing, from the natural-scientific point of view, about nothing at all, for 

 though, as we have seen, biology studies psychical phenomena, it does not 

 imply that it has anything to do with the impossible problem of what the 

 soul is or is not. And if we ask, quite apart from such metaphysical quibbles, 

 whether all observable material processes in the living organism or its parts 

 can be directly derived from known material processes in inanimate nature, 

 the answer even today must still be in the negative; those who have at- 

 tempted to do so have either reverted to gross schematism or else drawn a 

 bill on the possible progress of tomorrow — an unworthy manner of wrig- 

 gling out of the fact of the problem's insolubility. It may at once be assumed 

 that the future will bring us nearer the heart of the problem; whether it 

 will ever be entirely solved we know no more than the truth, laid down by 

 Herbert Spencer and many others, that the capacity for knowledge is limited 

 and the most general laws in existence must therefore remain unexplained. 

 Strictly speaking, the same causes have brought about the popularity 

 of the mechanistic theories of life as those that at one time produced so 

 many editions of Haeckel's Natural History oj Creation. It is obvious, however, 

 that a reaction against this conception of life was bound to set in, owing to 

 the disappointment felt over its splendid but unfulfilled promises. And so we 

 find, even before the turn of the century, vitalistic theories of life of various 

 kinds being produced, supported by representatives of no small importance, 

 as regards both their numbers and their attainments. And during the pres- 

 ent century their number has still further increased; true, they can nowhere 

 be said to have dominated the situation, but the part they have played has 

 been quite an important one, many of them having had a perceptible in- 

 fluence even in circles in which vitalistic or spiritualistic ideas have other- 

 wise never been very highly appreciated. They have for the most part come 

 from the physiologists, while the morphologists, v/ith far fewer exceptions. 



