28 THE AMERICAN BOTANIST 



asked to list the plants of a small lake with muddy shores, name 

 the water lily, cat-tail, arrow-leaf, pickerel weed, smait-w^eed, 

 blue flag, willow, red osier, alder, and many others and guar- 

 antee that more than 75% of them would be found growing 

 there. The ecologists who have been w'orking on this problem 

 for some time have now arrived at a point where they can pick 

 out the associations of plants that inhabit a definite locality, and 

 can also name the changes in the grouping that will be pro- 

 duced by more or less water, shade and the like. Plants of a 

 dry upland will be of one type when the soil is sandy and of 

 quite another when it consists of clay or calcareous loam, while 

 the addition of more moisture to any of these habitats will make 

 still other changes. This relationship of plants to their habitat 

 is found throughout the world, though the species foitning the 

 associations must of necessity change with the locality. It is 

 of interest to note, however, that while the species change, the 

 genera are much less likely to do so. All this is apropos of a 

 recent book by A. G. Tansley, entitled "Types of British Vege- 

 tation" in which the plant covering of the British Isles is dis- 

 cussed from this viewpoint. To American readers, its chief 

 value, aside from the very clear outlining of the various asso- 

 ciations will be the comparisons between our own flora and that 

 of Britain, which it for the first time makes possible. A large 

 number of the species are. of course, identical with our own, 

 while many others are closely related. The book runs to more 

 than 400 pages and is well illustrated by photographs of various 

 plant groups. It is pul)lished by the Cambridge University 

 Press for whom G. P. Putnam's Sons are agents in America. 

 The price is $2.00 net. 



The "General Science Outline" issued by Percy E. Rowell 

 in 1910 and reviewed in these pages has since been reprinted 

 by The MacMillan Company w^ith many additions and now 

 forms one of the best introductions to general sciences that 

 we have seen. The autiior lias succeeded admirably in select- 



