X50 THE HISTORY OF BIOLOGY 



in the organism, the idea of which he himself states that he borrowed from 

 Stahl. For just as the basis of Wolff's research work is the rejection of pre- 

 formation, so its final object is the abolition of "mechanical medicine" — 

 the theory that holds that the living body should be regarded and treated 

 as a machine, which finds the explanation of the phenomena of life in the 

 form and composition of the bodily parts, or, as it is expressly stated, in 

 anatomical principles. This theory Wolff declares to be a product of the 

 imagination and produces a number of arguments to prove its falseness. 

 Wolff, howe'' .:, never arrives at any properly worked-out vitalistic theory; 

 after all, he deals with the phenomena of the body along mechanical lines 

 and his "vis essetifialis" he does not identify, as Stahl did, with the soul. On 

 the whole, Wolff's theory is vague and inconsistent if we compare it with 

 Stahl's mode of thought, which is certainly hard to apprehend, but is never- 

 theless in its way loftily conceived. The most serious result of Wolff's phil- 

 osophical method, however, is that he fancies it capable of explaining 

 practically anything; with a couple of phrases he throws a bridge across 

 even the deepest abysses of natural science; he has a theory ready to hand to 

 explain even such phenomena as those in the face of which modern biology 

 has to be content with merely establishing the fact. In all this he is a pre- 

 cursor of the natural philosophy of romanticism, and it was, in fact, this 

 that eventually procured for his views the honour they deserved. 



His cellular theory 

 Wolff's treatise deals with the development of both plants and animals in 

 a constant endeavour to find factors common to both. In his opinion, the 

 growth of plants is due to the inner life-force drawing up moisture out of 

 the earth through the roots and into all the various parts of the plants; at the 

 points of growth this moisture is collected in especially large quantities; 

 through evaporation it acquires greater density and forms cuticles, which, 

 through fresh supplies of moisture, assume the form of ampulla;, the walls 

 of which are further thickened by evaporation, and the new ampulla force 

 themselves in between the earlier ones, whereby the substance of the plant 

 is renewed. The plant's vesicular system is formed through the circulating 

 sap's hollowing out ducts in the vegetable substance, the walls of these 

 ducts being likewise thickened by evaporation. The plant is then formed 

 by these ampulla; and ducts through a system of growth-forms, the abstract 

 and involved details of which it would take too long to follow. As mentioned 

 above, the florescence and germination are caused by a weakened growth — 

 "The adequate reason why within a certain period frondescence ceases and 

 germination begins is a diminution of the supply of alimental sap at the 

 point of growth, as is at once seen from the very definition of growth." 

 This is Wolff's scientific adduction of evidence. Similarly it is proved that 

 the germination and embryonic development consist in a renewed growth 



