SCIENTIFIC PROCEEDINGS 



Abstracts of Communications. 



Eighty-third Meeting. 



University and Bellevue Hospital Medical College, April 18, 1917. 

 President Gies in the chair. 



78 (1256) 



Quantitative experiments demonstrating the mechanism of the 

 inhibition of growth. 



By Jacques Loeb. 



[From the Laboratories of the Rockefeller Institute for Medical 



Research.] 



The problem of regeneration can also be stated in a negative 

 way, namely : Why do tissues and dormant anlagen of organs not 

 grow in an intact organism, while we know that they grow when 

 the buds or tissues are isolated? The laws of inhibition were 

 studied by a quantitative method. 



No notch of a leaf of Bryophyllum will grow while the leaf is 

 a part of the whole plant but the notches will grow when the leaf 

 is isolated. When a leaf is subdivided into as many pieces as 

 there are notches, each notch will give rise to a shoot; but if the 

 leaf remains intact only few will grow out. The writer concluded 

 that this again is a phenomenon of inhibition. 



This inhibition he had explained in former papers 1 as being 

 due to the fact that the inhibiting organ takes away the material 

 required for the growth of the inhibited organ. If this were the 

 case, we should expect that the total mass of shoots produced 

 by a leaf in a certain time is approximately the same no matter 

 whether the leaf produces few or numerous shoots. This is true 



1 Loeb, J., Bot. Gaz., 1915, LX, 249; 1916, LXII, 293; 1917, LXIII, 25. "The 

 Organism as a Whole," New York, 1916, p. 153. 



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