JAMAICA. 



BULLETIN 



OF THE 



BOTANICAL DEPARTMENT. 



New Series.] OCTOBER, NOVEMBER, 1897. VU1, iy - . 



1 Parts 10, 11. 



THE MOVEMENTS OF PLANTS. 



By Professor D. T. MacDougal, M.A., M S., Ph.D. 

 Lecture gicen at the Institute of Jamaica, June 19, 1897. 



It is a matter of common custom to consider motion as a special charac 

 teristic of the animal kingdom, and when attention is called to the more 

 apparent movements of certain well known plants, it is with the accom- 

 panying idea that it is something novel, sensational and exceptional rather 

 than general, and that this property does not properly belong to plants. 



It is pertinent to state, in the beginning of our discussion of the sub- 

 ject, that the power of movement is quite universally distributed among 

 plants and that but very few species may be found which do not exhibit 

 it in some form more or less easily observable. 



Although the general purposes of the movements of plants and animals 

 are identical, yet the general structure and mode of life of the two series of 

 organisms is so unlike, that the greatest possible differences are to be found 

 between the general character of the movements of plants and animals, 

 with respect to duration, rapidity, amplitude and immediate purpose, as 

 well as in the structure of the organs concerned in the movement, and 

 the mechanism of the elements of which these organs are composed. 



Asa matter of fact the movements of animals and plants are so much 

 unlike, that specific comparisons would be wholly unprofitable. In 

 general however it is to be said that the power of locomotion or move- 

 ment from place to place is exhibited by the greater majority of animals 

 and by but very few plants ; the movements of animals may be of great 

 amplitude, those of plants are quite limited in range ; the movements 

 of animals may be so rapid as to elude the eye, while those of plants are 

 generally so slow that they may be detected only by repeated and accu L 

 Tate measurements. 



The fundamental necessity for every organism whether plant or ani- 

 mal is the acquisition of a proper supply of food, and a secondary neces- 

 sity is the avoidance of danger, while the chief purpose of the organism 

 is reproduction or the preservation of the species. Movement is a very 

 important factor in the attainment of these objects, and the unlike 

 development of this power in plants and animals is due to the widely 

 dissimilar character and distribution of the food supply, and environ- 

 mental factors encountered by the two groups. 



In the consideration of this part of our subject, the time at our dispo- 

 sal will not permit us to pursue it to its utmost ramifications and we 

 may direct attention to a lew of the more important points only. 



The animal has developed in such manner that the high' r forms use 

 substances for food, which are not uniformly distributed throughout the 



