348 XEW JERSEY AGRICULTURAL COLLEGE 



together would continue to keep greep and grow after the stem 

 of one of them had been cut off from the root. Shoots of willows 

 and other plants, when planted upside down, would root and grow 

 as well as normally planted shoots. None of these experiments, 

 however, allowed an accurate study of the immediate effects pro-, 

 duced on the rate of growth by such a reversal of the current. To 

 permit this, the reversal must be brought about without any me^ 

 ehanical injury. This is possible in a plant like the sweet potato, 

 in which time of rooting, place of rooting and water supply of all 

 roots can easily he controlled by pot-growing in the greenhouse, 

 as sho^\m in Fig. 1. 



This preliminary report deals with that phase of the investiga- 

 tion in which the effect of the first reversal is studied. 



A study of Fig. 2 and the other results given reveals the fact 

 that from August 16th on, when the regular daily supply of Avater 

 was first witliheld, all parts of the plant, the watered as well as the 

 unwatered, were abruptly checked in their growth. Again, on Seii- 

 tember 5th, when one of the three sources of water supply was cut 

 off, without injury to the growing parts under study, all rapidly 

 growing parts (and possibly also the others), were checked again. 

 This checking of growth might be the result of an inadequate total 

 water supply, caused by the lack of water in two out of four pots 

 in M. B. and in the box, and two out of five pots in M. S. It must 

 be considered, however, that other branches were growing in the 

 greenhouse at the time which had made a growth of eight feet, were 

 growing at a rapid rate, and yet were rooted only at one joint in a 

 single pot. On the other hand, it is possible that the reversal of 

 the current per se interfered temporarily with a proper water sup- 

 ply to the well-watered, groA\nng parts. Experiments are now 

 under way to determine which of the two possi1>le explanations 

 advanced is correct. 



It is further of interest to note that the recovery of the rate 

 of gTOwth of S. B. 2 seems dependent on the rate of growth of 

 the watered parts. For example, from August 25th on, the rate 

 is rapidly increased, at the same time when the rate of the M. S. 

 is sinking to O or is maintained very feebly by its rosette. 

 Again, on September 18th, the rate drops soon to sink to a very 

 low level, at the time when the rosette of M. B. begins to grow 

 rapidly in several branches at once, making a total rate of lucre- 



