FIELD CROPS. 527 



Part 1 gives results of a study, continued during 1911-12, to ascertain " if the 

 improved sorts of cultivated hops from southern regions have a different rate 

 of growth in our northern climate from our wild-growing plants, which possibly 

 are better suited to the climate." 



Measurements of the hop stems were also taken at 6-hour i)eriods for several 

 days, and it was " found that the growth in length of hop stems under natural 

 conditions has a very distinct diurnal period, the rate of growth being smallest 

 during the night, greatest during the day. This periodicity is determined by 

 outer factors, among which the temperature has such a predominant influence 

 that under natural conditions it determines the rate of growth." 



Part 2 gives the results of observations made in 1913 by which it is shown 

 that " in experiments with vigorous 3-year-old hop plants, which were firmly 

 rooted in an open glass (cold) house, the stems were found to show during May 

 and June a rotational movement amounting on an average for 1 to 2 weelis' 

 observations to about 120° per hour or one-third of the rate of the minute hand 

 of the clock. 



" On closer study the rotational movement proved, like the growth in length, 

 to have a very distinct daily periodicity, the rate being greatest during the day, 

 least at night. Further, the experiments showed that this daily periodicity is 

 determined by external factors, among which the temperature is of such domi- 

 nating importance that its variation under natural conditions is determinative 

 for the rate of rotation. A graphic comparison of the fluctuations in the rate 

 of rotation and degree of humidity shows that there is no connection between 

 them under the natural conditions prevailing when the observations were car- 

 ried out. 



" From laboratory experiments in June with pot plants, which were placed 

 alternately in the light and dark, under otherwise uniform external conditions 

 as far as possible, it appeared that the rotational movement is not different, at 

 any rate not essentially different, in the dark and in scattered daylight. Ex- 

 periments carried out in a cellar with constant low temi)erature showed that the 

 minimum temperature for the rotational movement, just as for the growth in 

 length, lies in the neighborhood of 4°. 



"An endeavor has been made with the minimum temperature as starting 

 point to obtain an expression of the relative quantities of heat which were of 

 importance for the rate of rotation under the main experiment. The numbers 

 obtained, which are called ' active quantities of heat ', show that there is a very 

 complete agreement between fluctuations in these and in the rate of rotation, 

 the fluctuations showing a perfect sjmchronization under the conditions observed. 



"A comparative experiment with twining bean plants showed that quite a 

 similar daily periodicity in the growth in length and rate of rotation of the 

 stem can also be seen in them and is also determined here by the temperature. 

 It is probable that the growth movements in many plants living under climatic 

 conditions such as ours, where great temperature fluctuations occur in a diuiiial 

 period, have a diurnal periodicity which follows that of the temperature." 



Fertilizer experiments by the German Hop Culture Association with 

 phonolite meal and 40 per cent potash salt in 1913, F. Wagnee (Prakt. Bl. 

 Pflan^enhau u. Schiitz, n. sen, 12 {WU, Nos. 1, pp. 9-12; 2, pp. 22, 3.3).— This 

 paper reports a continuation of work previously noted (E. S. R., 30, p. 527), 

 and gives results that show superiority of the potash salt over phonolite 

 meal, both by direct application and in its after effect. 



Tests of selections from hybrids and commercial varieties of oats, C. W. 

 Warbukton, L. C. Burnett, and H. H. Love {U. S. Dept. Agr. Bui. 99 {1914), 

 pp. 25, figs. 6). — Results of comparative yield tests are reported between numer- 



