181 
table life since Jurassic times, with special reference to the Creta- 
ceous or Tertiary floras which have been identified in the region 
under discussion. With the advent of the Ice Age of course all 
these were destroyed except such as could migrate or exist south- 
ward. The author concludes. that of all these “none showed 
greater capacity for variation and improvement than the ancestral 
forms of the modern dominant family of the Composite,” whose 
seeds could fly before the prevailing north winds or attach them- 
selves to the fur of migrating animals, and would be assisted on 
their return by similar influences. Necessarily the changes in 
soil, climate and topography would so alter the conditions that a 
majority of the species could not exist over the region once occu- 
pied by them. Others perished by the way, and most of them 
were modified in one direction or another in their Tertiary south- 
ward migration and their subsequent northward migration in recent 
times. 
At the present day the same or similar forces are at work chang- 
ing or modifying the distribution and structure of plants, but a 
new element, the influence of man, is now at work. Thus in the 
Minnesota valley he is responsible, according to the author, for the 
introduction and establishment of 130 alien forms and the exter- 
mination of many native ones from localities where they were once 
abundant. 
Under the statistical discussion of the facts, which occupies 
about 150 pages, at the close of the volume, may be found a great 
many interesting and often significant results and comparisons, 
which want of space does not permit us to review. 
A complete family, generic and specific index, with syno- 
nyms in italics, terminates the work. It could hardly be rendered 
more exhaustive, and may be taken as a type of what such books 
should be. We trust that the author has in mind a work which 
shall cover the Archegoniatz and that it will be carried to comple- 
tion in the same thorough, conscientious and progressive spirit. 
Fis: 
Monarda fistulosa—Notes on, and the Phenomenon of Fertilization 
in the Flowers of. Thomas Meehan, Ida A. Keller (Proc. Acad. 
Nat. Sci. Phila., 1892, 449-454; one plate; reprinted). 
