THE LIVING ENVIRONMENT. 117 



adaptations in its tissue developments, mode of 

 growth and so forth. 



This toleration is perhaps most marked in the 

 case of those cereals which, though infected by the 

 minute mycelium of Ustilago while still a seedling, 

 nevertheless go on growing as apparently healthy 

 green plants indistinguishable from the rest, al- 

 though the fine hyphae of the parasite are in 

 the tissues and keeping pace with the growth of 

 the shoots just behind the growing points. As the 

 grains of the cereal begin to form and swell, how- 

 ever, the hyphae suddenly assume the part of a 

 dominant aggressor, consume the endosperm of 

 the enlarging seed, and replace the contents of 

 the grain with the well-known black spores known 

 as Smut. 



Notes to Chapter XII. 



The reader will find a summary of such fungi as are 

 here concerned in Massee, A Text-Book of Plant Diseases, 

 1899, or Prilleux, Maladies dcs Plantcs Agricolcs. 



For further details the student should consult the works 

 of Frank and Sorauer referred to in the notes to Chapter 

 IX., and Tubeuf, T/ie Diseases of Plants, Engl. ed. 1897, 



pp. 104-539- 



For experiments on the effects of grass on orchard trees, 

 see Report of the Woburn Experimental Fruit Farm, 1 900, 

 p. 160. 



For the further study of weeds, the interesting bulletins of 

 the Kansas State Agricultural College, 1895- 1898, will show 

 the reader what may be done in the matter of classifying 

 them according to their biological peculiarities. 



In regard to insects, the reader will find the following fist 

 embraces the subject : Somer\-ille, Farm and Garden Insects, 



