RECENT ADVANCES IN SCIENCE 49 



introduction of semi-mystical terms, " cloaks for ignorance," 

 as an American writer has termed them: " biological error," 

 " limiting factor," " inhibition factor," "antagonism," and 

 even the term " stimulus " has been subjected to much ill-use. 



The main development of this phase of plant physiology- 

 has taken place on the Continent of Europe, with its sequel 

 of lively controversies, but it may be interesting if examples 

 are cited from this country and from America representing 

 extreme views on the matter. 



As an example of the philosophical school of thought, one 

 may quote from the recent work of a physiologist (J. S. Hal- 

 dane, The New Physiology, London, 1919)- "The problem of 

 physiology is not to obtain piecemeal physico-chemical ex- 

 planations of physiological processes, but to discover by 

 observation and experiment the relation to one another of all 

 the details of structure and activity in each organism as ex- 

 pressions of its nature as an organism." " For biological 

 phenomena the schematised physical conceptions are insuffi- 

 cient practically, and we must therefore make use of special 

 biological conceptions, the relation of which to the physical 

 conceptions must for the present remain more or less obscure 

 for the lack of data." " That a meeting-point between biology 

 and physical science may at some time be found there is no 

 reason for doubting, but we may confidently predict that if 

 that meeting-point is found, and one of the two sciences is 

 swallowed up, that one will not be biology." 



As a contrast to this one may refer to the recent researches 

 of J. Loeb on Regeneration in Bryophyllum. This writer has 

 obviously taken the point of view that the rather philosophical 

 method of observation of European writers has not led to any 

 great success. All previous work is therefore ignored and the 

 author starts afresh to carry out quantitative experiments 

 which can be interpreted according to the ordinary laws of 

 physics and chemistry. To quote this author (" The Law 

 Controlling the Quantity of Regeneration in Bryophyllum 

 calycinum," Journ. Gen. Physiol. 191 8, 1, pp. 81-96): "This 

 law shows that the problem of regeneration is part of the 

 problem of growth, and that it falls under the law of chemical 

 mass-action." Whether this drastic statement can be sub- 

 stantiated by further research remains to be seen, but one 

 seems to detect in subsequent papers on the same subject 



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