APR. 4, 1923 CLARK: ORIGIN OF VERTEBRATES 129 
were analyzed. The quality of these waters and the source of their 
mineral content are discussed in the report. 
It is thus apparent that the reconnaissance has yielded results that 
are important contributions to the geologic history of the West Indian 
region. It has also yielded results that in many ways have an intimate 
bearing on the welfare of the inhabitants of the Republic—results 
based on an understanding of the geologic features derived from ob- 
servations that at first glance may seem to be of purely scientific in- 
terest only. 
BIOLOGY.—The origin of the vertebrates. Austin H. Cuarx, Na- 
tional Museum. 
Heretofore all the writers on the subject of the evolution of the 
vertebrates have approached the problem with the complex vertebrate 
structure admittedly or unconsciously dominating the perspective 
within which all other types of animal structure should fall. Under 
the influence of this preconceived though unconfessed idea either a 
devious line was traced from the vertebrates through progressively 
simpler forms eventually ending in the protozoans, or a line was drawn 
from the protozoans to the vertebrates from which more or less numer- 
ous side branches were given off terminating blindly in supposedly 
anomalous types. 
It never seems to have been noticed that animals and plants are 
but slightly different manifestations of the same organic phenomena, 
and that therefore there is no reason to suppose that the evolutionary 
line in one kingdom would be in its broader features greatly different 
from that in the other. 
In the following pages I shall attempt to show that if we consider 
the phanerogam-like radially symmetrical colonial coelenterate type 
as representing the culmination of animal evolution properly so called, 
and the bilateral animals as having arisen through the disruption of 
this type and the gradual geometrical recombination of the characters 
of the forms resulting from this disintegration, we shall have an ex- 
planation of the origin of all the different animal types by which each 
and every one is allocated and shown to be a necessary element in the 
general plan. 
The embryological processes common to all animals show that the 
egg develops into a blastula which subsequently becomes a gastrula; 
‘but from this point onward the developmental processes exhibit no 
features common to all animal types. 
