THE PROTOPLAST AS HOUSEBUILDER 



45 



and the seeds of Wheat and Maize about 75 and 85 per cent, respectively. 

 The fruit of Artocarpus incisa 



The Bread-tree, which, without the ploughshare, yields 

 The unreaped harvests of unfurrowed fields ; 

 And bakes its unadulterated loaves 

 Without a furnace 



yields about 3^ per cent. 



Starch-grains vary considerably in size, according to the plants in which 

 they are found. Some of 

 the largest occur in the 

 tubers of Canna edulis, and 

 measure ^^th of an inch in 

 diameter. This is the inter- 

 esting Tous-les-mois starch 

 of commerce. The grains 

 differ very much in form 

 also, but ovoid and lens 

 shapes are most common. 

 Spherical grains are found 

 in the tuberous roots of 

 plants of the Orchid family, 

 and rod and bone shapes 

 in the milk-sap of many 

 tropical Euphorbias. In the 

 Corncockle (Agrostemma 

 githago) they are spindle 

 shaped ; and angular starch 

 granules, .cemented together 

 to form ellipsoidal grains, 

 are found in the seeds of 

 the Oat (Avena) and Rice- 

 plant (Oryza). 



Closely allied to starch 

 is inulin (C 6 H 10 5 ), which is 

 found in solution in many 

 roots, tubers, seeds, etc. 



particularly of plants of the Composite order. Thus it occurs in the 

 roots of Elecampane (Inula helenium}. Dandelion (Taraxacum officinale), 

 Chicory (Cichorium], and Feverfew (Matricaria parthenium) ; in the 

 tubers of the Potato-plant (Solanum tuberosum), Dahlia, and Jerusalem 

 Artichoke (Helianthus tuberosus) ; and in the seeds of the Sunflower 

 (H. annuus) and many other plants. The inulin of the chemist, which is 

 a soft, white, tasteless powder, is usually prepared from Elecampane or 

 the Dahlia. In its natural state inulin is distinguished from starch by 



Photo by"] [E. Step. 



FIG. 69. CUCKOO-PINT (Arum maculatum). 



A familiar hedgerow plant whose tubers are rich in starch. About one- 

 third the natural size. EUROPE, N. AFRICA. 



