REVIEWS 285 
here merely to give the titles of the chapters: chap. iv, ‘The Origins 
of Animal Life and Evolution of the Invertebrates’’; chap. v, ‘‘ Visible 
and Invisible Evolution of the Vertebrates’”’; chap. vi, ‘‘ Evolution of 
Body Form in the Fishes and Amphibia”’; chap. vii, “Form Evolution 
of the Reptiles and Birds’’; chap. viii, ‘Evolution of the Mammals.” 
The author is consistent throughout in viewing the organism as an 
energy complex. A great carnivorous Tyrannosaurus, for example, is 
chosen as a culmination of the offensive type of energy complex, while 
the horned herbivorous dinosaurs, known as Ceratopsia, are viewed as a 
defensive energy complex. The evolution of these two highly specialized 
complexes is an example of the ‘“‘counteracting evolution”’ of offensive 
and defensive adaptations. 
The book is so full of meat that the reviewer finds himself at a loss 
to do it justice in a limited space. So many stimulating suggestions 
are made in every chapter, indeed on almost every page, that one must 
read it carefully to get its full import. While there are many points 
that invite controversy, it must be borne in mind that the evident inten- 
tion of the author is merely to establish a new threshold for departure, 
not to make an exhaustive explanation of evolutionary phenomena. 
The way toward future research in many lines is pointed out and a con- 
structive plan for future work is outlined. This in itself is a contribu- 
tion of the highest importance, since it places a new milestone beside 
that long and ancient highway of ‘“‘the evolution of the evolution idea.”’ 
EN. 
Organic Evolution, a Text-Book. By RicHARD SWANN LULL. 
New York: Macmillan, 1917. 
This compact volume of seven hundred and twenty-six pages and 
nearly three hundred figures, by the distinguished professor of vertebrate 
paleontology of Yale University, is one of the most satisfactory texts 
on organic evolution known to the writer. Especially satisfactory is it 
from the side of paleontology, and paleontology is and must remain the 
clearing house of all evolutional theories and doctrines. It treats of the 
history of the evolutional doctrine; the accepted and disputed factors 
of organic evolution; and the evidences of evolution, drawn from living 
and fossil organisms, including the origin of vertebrate life and of its 
chief groups; the adaptation, especially of vertebrates, to terrestrial, 
cursorial, volant, aquatic, desert, and cave life; the evolution of some of 
the best known types of mammals, the horses, elephants, camels, and, 
