10 



PRINCIPLES OF PLANT- TERATOLOGY. 



and the practically infinite multitude of interwoven 

 analyses and syntheses it presupposes, our understand- 

 ings recoil disconcerted. That the simple play of 

 chemical and physical forces, left to themselves, should 

 have worked this marvel we find hard to believe."* 



Many abnormalities which are of the nature of 

 reversions, as in the case of the forking of the alternate 

 leaves at every node on the shoot of Ulmus glabra, 

 seem also to be definite variations, and also, in a sense, 

 purposive adaptations, for, under the influence of 

 abnormal stimuli, whereby the balance of the organism 

 becomes upset, latent ancestral tendencies or traits are 

 brought to the surface, resulting in a form which 

 represents the best response which the plant can make 

 to the unusual conditions. 



Hence, the Sachs-Groebel theory of " material and 

 form"t seems to fall, as it assumes that "the differences 

 in the forms of the organs of plants depend upon [i. e. 

 are due to or caused by] differences in their material 

 components, and that the variations in the organic 

 forms result from variations in the processes of nutri- 

 tion. Thus the substances which give rise to the 

 formation of a foliage-leaf are different from those 

 which lead to the formation of a carpellary leaf. If this 

 be so, the causative^ action of the so-called morpho- 

 logical processes may be admitted, etc." Here the 

 mechanism employed to bring about a result is alone 



* ' Creative Evolution,' p. 263, 1014 : How different is this conclusion from 

 that of Farmer, for example, who is one of that school whose views the 

 present work is designed to oppose : "Organic form may be regarded as a 

 necessary outcome of the combination of matter and force, without reference 

 to any teleological consideration of use or the reverse " ! (" Stimulus and 

 Mechanism as Factors in Organisation," 'New Phytologist,' vol. ii, 1903, p. 

 193). 



t ' Stoff und Form.' 



X No causality (in the true sense of the word) can ever be attributed to 

 purely mechanistic processes, such as are involved in all these cases. The 

 purely blind chemico-physical energies must be ruled out as the controlling 

 and regulating agents in organization. Theirs is a much more subordinate 

 role. The whole problem is outside the true domain of physical science, and 

 cannot be solved by its method ; one of the mistakes made by writers like H. 

 Elliot ("A Survey of the Problem of Vitalism,"' 'Science Progress,' Jan., 1915) 

 lies in supposing that the methods of physical science can be applied to 

 the whole series of known phenomena. The agnostic attitude of Mercier 

 is rather to be preferred. 



