SYMBIOSIS. 339 



general, according to the circumstances. Many animals are 



^n'.; 379— Roots of a yellow Gerardia, C, attached to tlie ruol of a blueberry bush, />'. 

 Ihey enlarge at tile points of contact and there send hausti.ria into the Imst root. 

 NatiirU size.— After (h-ay. 



thus preyed upon b)' bacteria and fungi. jNIost communi- 

 cable diseases, such as t3'phoid fever, diphtheria, and tuber- 



•'■^^^■^i^y^yy •^--- y>yyi<yy^,<y 



p. 



A 



Fig. 3S0. — A, European dodder twining about a liop stem. All but tlie uppermost coils 

 show the groups of wartlike s^^■ellings Irom wliich haustoria petietrate the host stem. 

 Natural size. A, Germination of same. The various stages are arranged in order 

 from right to left. In tlie last stage the seedling has found a suitable support and has 

 absorbed all the reserve food in tlie thickened lower end, which lias \\ithcred and died, 

 freeing the plant from the ground. Magnified about 2 diam.— After Kerner. 



