EXPERIMENT STATION REPORT. 349 



ment of about seven and one-half inches. This suggests that the 

 two currents, which must from a certain point in both the M. S. 

 and M. B. flow to opposite sides, may vary considerably in 

 strength. 



Furthermore, the total amount of increment in length of all 

 three branches plotted in Fig. 2 never reached the total after 

 August 16th which it had before. This would be still more 

 striking if all the smaller branches were taken into consideration 

 which stopped growth altogether. 



It may be objected that the appearance of faseiation, which is 

 very common in some varieties of Ipomoea batatas, interferes 

 with the results. The experiment will be repeated with other 

 plants, if necessary with other varieties; but it is shown in this 

 paper how both the M. B. and the M. S. made their heaviest 

 growth after they became fasciated. 



In Strasburger's experiments, in which the course of the water 

 current in inverted plants was traced with eosin, the water flowed 

 reversely up the stem and descended the branches in the order in 

 which they were met on the way. If in a living plant a reverse 

 current would flow accordingly and continue to flow so, in case 

 of an insufiicient amount of water the branches farthest away 

 from the water supply would be the first to dry up. In the present 

 experiment, however, the three branches farthest away from both 

 main supplies of w^ater were the only ones which did not dry up. 

 S. B. 1, 2 and 3 are the three most basal branches of M. B. If 

 they got their water from C and D, the current passed all the 

 smaller branches on the way without nourishing them sufficiently 

 to gi-OAv or even to keep alive. If the water came from pots 3-6, 

 it passed the smaller branches on that side and then went into 

 ^[. B., from w^here it ascended in the normal direction. That 

 seems to point again to the conclusion that it was not the dimin- 

 ished water supply, but the direction of the water current, which 

 caused the disturbance in the rate of growth. 



Whether the reversal of the comparative rates of growth in the 

 four branches of the S. B. 3 before and after September 5th is 

 sig-nificant, further experiments must decide. In the field non- 

 fasciated sweet potato vines have never been observed by the 

 writer to have the apical branches developed faster than the basal 

 ones. 



