JACQUES LOEB 657 



SUMMARY. 



This paper contains the results of a reexamination of a law expressed 

 in a previous paper; namely, that when a piece of stem inhibits the 

 growth of shoots and roots in a leaf connected with it the dry weight 

 of the stem increases and that this gain equals approximately the mass 

 of shoots and roots the leaf would have produced if it had been de- 

 tached from the stem. This has been confirmed and it has been 

 shown that the gain of the stem as a rule even exceeds slightly the 

 mass of shoots and roots the leaf would have produced if it had not 

 been inhibited by the stem. This supports the idea that the inhibi- 

 tory influence of the stem upon the formation of roots and shoots in 

 the leaf is due to the fact that the material available and required 

 for this process naturally flows into the stem. 



