24 THE BOOK OF NATURE STUDY 



of the fruit becomes dry, and when ripe the upper parts of the 

 carpels below the projecting rim bend back, leaving a number of 

 small holes leading into the cavity of the ovary. 

 Through them, as the fruit sways on its long stalk, 

 the small seeds are shaken out like pepper from a 

 pepper-castor. 



If a leaf of the Poppy be broken off or the flower- 

 stalk cut across, drops of white milky j uice will exude 

 FIG. 7.-^Fruit of from the cut surfaces. Cutting across the tissues 

 the Red Poppy, has broken a number of minute tubes containing 

 T l! e JT eS b 7 this flui( i, which then oozes out, much as blood does 



which the seeds 



escape are seen when the minute capillary vessels of the human 

 just below the s kin are injured. A similar milky juice is found 

 margin of the j th Dandelion, the Periwinkle, and some other 



stigma. (After 



Baiiion.) plants. In the Poppy this juice, the use of which 



to the plant is not properly understood, is of 



special interest, since opium is obtained from the dried milk exuding 



from cuts made in the young fruits of the Opium Poppy (Papaver 



somniferum) . 



THE GARDEN PEA (Pisum sativum, L.) 



The ordinary Garden or Edible Pea, material of which can be 

 obtained from any kitchen garden, is a most interesting plant 

 to study. It can readily be followed through its complete life- 

 history by sowing seeds in spring or early summer in the school 

 garden. The seeds, which have been removed from pods borne on 

 plants of the preceding year, are large, and their structure should 

 be carefully made out. The seed-coat will be found to show the 

 scar of the stalk by which it was attached to the pod. Within 

 the seed-coat will be found the large embryo plant, ready to con- 

 tinue its growth when the seed is planted. In this we distinguish 

 already the young root and shoot, and a pair of seed-leaves or 

 cotyledons. These are swollen hemispherical structures very un- 

 like ordinary leaves. They have become devoted to the function 

 of store-houses for the food material at the expense of which the 

 young plant will commence to grow. The structure of the seed 

 is shown in the model which forms the frontispiece to this volume. 



In germination the root extends down into the soil and 



