352 



PHYSIOLOGY OF NUTRITION. 



nieiit is indicated in the drawing below. The short piece, 45 mm. 

 iri length, below the ring has produced small roots ; from the 



portion above the ring long 

 roots have been put out, and 

 at the upper end shoots also. 

 The reason that only short 

 roots are produced in the 

 short length below the ring- 

 is to be sought in the f act- 

 that here an insufficient 

 quantity of plastic material 

 is available. The small 

 quantity of nitrogenous and 

 non-nitrogenous formative 

 material in the part of the 

 shoot below the ring is 

 rapidly used up. Non-nitro- 

 genous substances may, it is 

 true, still stream to it, for 

 it can be readily determined 

 (for method see 110) that, 

 especially in the peripheral 

 region of the wood, much 

 starch is present, as I satis- 

 fied myself, e.g., in February, 

 using a branch of Salix 

 fragilis, 6 mm. in diameter. 

 But the ringing stops the 

 conduction of proteids which, 

 as the ringing experiments 

 themselves and other obser- 

 vations teach (see 143), is 

 chiefly effected by the ele- 

 ments of the soft bast. 

 Naturally the formation of 

 roots below the ring is more 

 vigorous the higher the place 



on the branch from which the ring of cortex is removed. On 

 the other hand, no formation of roots at all took below the 

 ring when the short piece at the lower end of the branch was 

 only 20 mm. in length. If we do not remove a complete ring, but 



FIG. 11G. Ringed branch of Salix fragilis, in 

 the upper part of -which vigorous roots and 

 shoots have developed. 



