Cucurbita maxima and C. Pepo. 47 



Darwin has shown in his several works, in a very careful and 

 painstaking manner, how the movements of plants are produced 

 or modified in certain organs by various mechanical influences, 

 as well as by natural conditions to which plants are ordinarily 

 subjected. He has also shown us what direction these move- 

 ments take and the figures they describe, and to his first paper 

 on Climbing Plants, in the Journal of the Linngean Society for 

 1865, was due the suggestion that, if these movements are but 

 normal manifestations of growth, dependent upon the perfect 

 maintenance of the vital condition of the plant, they must 

 necessarily be affected by whatever operates in any manner — 

 whether to augment or diminish — the physiological changes 

 in, and conditions of the plant as a whole ; and, therefore, that 

 they must afford a ready means of determining the effect of 

 varying meteorological conditions upon growth, and those 

 which are best adapted to its promotion. It was, therefore, 

 with this idea in mind, that the experiments here recorded 

 were undertaken. It was recognized as of prime importance 

 that, to secure results which should be of the greatest value, the 

 plants must be grown in the open air and under the varying 

 conditions to which they would be naturally subjected. It was 

 also thought desirable to select a plant of vigorous growth, in 

 which movements were sufficiently pronounced and rapid to per- 

 mit of frequent and accurate observation. The mammoth squash 

 {Cucurbita maxima) was found to answer the requirements bet- 

 ter than any other plant obtainable. With this, all the original 

 experiments were obtained, but during the past summer, 0. 

 pepo was used for the purpose of confirmation and to gain in- 

 formation upon one or two additional points of minor impor- 

 tance. This was possible, since the structure of the tendrils 

 and also their movements are the same in each case, so that 

 our remarks may apply equally well to both species-, and 

 doubtless to a very large extent, to the entire family. 



Seeds of the mammoth squash were planted in a carefully 

 prepared lot, sufficiently removed from trees and buildings to 

 prevent the plant being subject to any but the normal condi- 

 tions of light, air, temperature and moisture. As soon as 

 the vines were long enough, they were carefully trained 

 from west to east, their branches being allowed to run in what- 

 ever direction they might choose. The tendrils, upon which 

 observations were made, were in some cases selected as soon 

 as they became straight and active, in other cases not until they 

 had been moving for some hours or perhaps a day. The aim, 

 however, was to record the movements for as many consecu- 

 tive hours of night and day, during the entire period of growth, 

 as possible. Through variation in movement of the tendrils 

 and terminal bud, rate of growth in the vine and weight of the 



