402 LSSSOJSrS WITS PLANTS 



such a purpose, or, in fact, that they were devel- 

 oped primarily as a means of enabling the plant 

 to climb. 



SuGQKSTiONS. — We have thus seen how some plants are able to 

 maintain themselves in the fierce struggle for existence. Let the 

 pupil observe if climbing plants naturally grow with other and tall 

 plants, or do they frequent places of less competition and run their 

 chances of finding support on other things than growing plants. Does 

 the climbing habit impress the pupil as being a means ot enabling the 

 plant to reach light and air 1 In respect to the methods by which 

 plants climb, any climber will afford interesting study, but the teacher 

 will find young morning-glory, pea, pole bean, Japanese hop, cucum- 

 ber, and nasturtium plants to be easily grown from seeds and useful 

 in demonstration. Darwin's "Movements and Habits of Climbing 

 Plants " should be consulted. 



LXXVIII. VARIOUS MOVEMENTS OF PLANTS 



508. With Fig. 82 we studied the form of the 

 leaf of bean, but there is more to be seen in 

 the picture. The leaf at the left was drawn in 

 the day-time, that at the right in the night-time. 

 There are similar differences in the positions of 

 leaflets of oxalis (Figs. 422, 423) or wood- sorrel. 

 Observe, also, at day and night, the leaves of 

 clovers, lupines, locusts and acacias. In other 

 words, the leaflets and leaves of many plants, 

 notably of the Leguminosse, take different positions 

 at day and at night. The leaves' of some plants 

 close up during very hot hours of the day. The 



