48 



REGENERATION 



38.7 milligrams of shoots per gram of stem, practically identical 

 results. 



It is therefore obvious that the dry weight of the sum of the 

 shoots produced by the small pieces a', h' , and c', d' , approxi- 

 mately equals the dry weight of the shoots produced by the big 

 pieces, o, 6, c, and d (Fig. 39), or, in other words, the mass of 

 shoot produced at the apex of the large pieces is approximately 

 equal to the dry weight of the shoots the same stems would have 

 produced had the buds of every second node been able to grow. 



Table XV 



Experi- 

 ment 

 No. 



Duration of 

 experiment 



Number of pieces 



Shoots 

 pro- 

 duced 

 per 

 gram of 

 stem, 

 milli- 

 grams 



II 



1921 



Nov. 3- 

 Dec. 6. "i 



1921-22 



Dec. 8- 

 Jan. 10. 



7 four-node pieces, a, h, c, 



d. 

 14 small pieces, a', b', c', 



d'. 



16 four-node pieces, a, b, 



c, d. 

 32 two-node pieces, a', b', 



c\ d'. 



36.0 



38.7 



45.0 



39.5 



3. Further Experiments on Small and Large Pieces of the 

 Same Stem. — A third series of experiments was as follows: 

 Long pieces of stem, containing about 10 nodes, were cut out from 

 the same plant which was more than 1 year old (Fig. 40). The 

 middle piece of about 6 nodes (piece 3 in Fig. 40) served for the 

 experiment, and two small pieces, 4 and 5, containing 1 node 

 each, situated basally from the large middle piece in the same 

 stem, serving as controls. In other experiments of the same 

 character pieces containing about 14 nodes were cut out from 

 the stem of the same plant; 2 small pieces at the base, each con- 

 taining 2 nodes (4 and 5, Fig. 41), were used as controls, while 

 the middle piece (3, Fig. 41) served for the main experiment. 

 All the pieces dipped with their base into water. 



It is obvious from Figs. 40 and 41 that the large pieces of stem 

 (3) produced larger masses of shoots than the small pieces 1 and 



