The effects of cutting secondary roots on the growth of primary 

 roots is shown in the two preceding tables. In one case the experi- 

 ment lasted seven days and in the other forty-nine days. In one 

 experiment, Table XIII, the secondary roots were cut only once. 

 In the experiment shown in Table XIV they were cut as often as 

 they appeared, and in the latter case there occurred 59 sec- 

 ondary roots on the normal and an average of 229 on the cut plants. 

 On one of the cut plants there also appeared fifty-one additional 

 secondary roots on the stem above the seed. In both experiments a 

 large acceleration took place in the growth of the primary 

 roots. In Table XIII there is shown a slight retartlation at the time 

 of the first measurement. Recovery was so quick in this instance 

 that the usual degree of retardation was hardly perceptible. Had 

 observation, however, been made during briefer periods than twenty- 

 four hours a decided retardation would have been seen, inasmuch as 

 the first effect of the shock caused by cutting is invariably a greatly 

 retarded growth. The nearer the cutting to those parts of the plants 

 under observation the more pronounced is the retardation. The 

 retardation apparently manifested itself very quickly after mutilation, 

 and the accelerated growth is very pronounced in this instance. The 

 effects of mutilation on organs in which measurements were made 

 during shorter periods of time can be seen from the following table. 



Table X^^ Experiment showing the effects of splitting primary roots 

 upon the growth of stems (hypocotyls) of Lupinus luteus, 

 L. 18 plants used, 9 normal and 9 split roots. Primary 

 roots split between points 20 and 30 millimeters from their 

 apexes. Plants cultivated in sawdust. Growth of normal 

 plants equals loo^/r. 



Average growth in niillimeters. (Hours.) 

 6 12 24 4S 72 g6 



Normal 1.6 2.2 5.1 ii.5 8.1 9.3 



Split 0.7 2.1 5.1 12.5 8.S 9.8 



Percentage ) Period growth 44*7^ 95yf loo'/f 109''/ io2yr 105*/^ 



Split to unsplit ) Total growth 102'J'i: 



Original length of roots, 31 millimeters. 



The first measurements made six hours after cutting shewed a fall- 

 ing oft" of 56''/ in the growth of the split roots. A greater retarda- 



