168 ECOLOGY 



carefully on the tips of the glandular hairs, note what movements, if 

 any, occur, make sketches of the leaf in various positions, and keep a 

 complete daily record of the behavior of the leaf until it returns to its 

 ordinary form. 



References for Sees. 145, 146. Darwin, 64 ; Darwin and Acton, 11. 



HOW PLANTS PEOTECT THEMSELVES FROM ANIMALS 



147. Field study. If possible, visit pastures grazed by horses, cattle, or 

 sheep, and large barnyards where weeds are abundant. Make a sketch map 

 of a small part of the pasture or barnyard, showing the clumps of weeds 

 that have been left uneaten ; number the clumps, and at the bottom of the 

 map indicate what plants make up each group. Study the characteristics of 

 some plants that are not usually eaten, and state the most obvious means of 

 protection of each plant. 



148. Laboratory study. Examine in detail any of the plants of your region 

 which are. left unharmed by grazing animals, and make out a tabular list 

 of the protective equipment of each plant. Use the microscope to study 

 and make sketches of cutting edges of grasses and sedges and the rough or 

 stinging hairs or spines of such plants as mulleins, nettles, thistles, and so on. 

 Do not taste plants suspected of being poisonous, but try those which are 

 known not to be so. If some plants are attacked by insects, though not by 

 grazing quadrupeds, make a note of it. Record the notes in a table like 

 the one on the following page.' 



POLLINATION OF FLOWEES 



149. Studies in insect pollination.** The student cannot gather more than 

 a very imperfect knowledge of the details of cross pollination in flowers with- 

 out actually watching some of them as they grow and observing their insect 

 visitors. If the latter are caught and dropped into a wide-mouthed, stop- 

 pered bottle containing a bit of cotton saturated with chloroform, most of 

 them may be identified by any one who is familiar with our common insects. 

 The insects may be observed and classified in a general way into butterflies, 

 moths, bees, flies, wasps, and beetles, without being captured or molested. 



Whether these out-of-door studies are made or not, several flowers should 

 be carefully examined and described as regards their arrangements for 

 attracting and utilizing insect or bird visitors. 



1 It will probably be necessary for the instructor to determine for the student 

 many of the species studied. 



