90 THE AMERICAN BOTANIST 



much larger group, called saprophytes, do not attack plant and 

 animal bodies until dead though they may Vne on matter ex- 

 creted by living things. In the latter group there is great di- 

 versity of habit and habitat. The minute species often select 

 the most unusual places for growth. One lives in the human 

 ear, feeding on the secretions from its lining, another is re- 

 stricted t(» the hoofs and horns of animals. Some occur only 

 on burnt ground and one lives on old rope or paper. Still 

 another lives on wasp nests and a large number grow on the 

 droppings of different animals. Some kinds find their exis- 

 tence limited to a single species and if they do not find this 

 species they do not survive. One is confined to the dead stems 

 of the bullrush another to rotting beech wood, another to 

 maple etc. Other forms have a wider choice of habitats but 

 still are confined to single families of plants as the grasses 

 or cresses. There is still another group of nearly ten thous- 

 and species that pass practically half their life cycle on one 

 species of plant and then change to another. A group so large 

 and so varied as the one we have described cannot be ade- 

 cjuately presented in a single volume and it is customary for 

 authors to select some division of it for treatment. Among 

 favorite groups for such selection are the bacteria, the yeasts 

 and the mushrooms. In a new volume by Dame Helen Gwinne- 

 \^aughan, professor of botany in the University of London, 

 the Ascomycetes, the Uredinales and the Ustillaginales are 

 discussed. The book is an octavo volume of 230 pages and 

 bears the title of "Fungi". It is one of the Cambridge Bo- 

 tanical Handbooks being issued under the editiorial supervis- 

 ion of A. C. Seward and A. G. Tansley. The author has 

 packed into the book an unusual amount of significant ma- 

 terial which brings our knowledge of this group of plants up 

 to date. Owing to the technical aspects of the subject the 



