INVERTEBRATES. PROTOZOA 2 
old before America was even discovered. The specimens show cross, 
longitude and oblique sections of the wood finished and unfinished, 
and the labels on the specimens give the distribution of the species, the 
characteristics of the wood and its economic uses. The trees are 
grouped by families and the location of each family will be found on the 
floor plan at the entrance of the hall. The reproductions of the flowers, 
leaves and fruits in natural size are instructive. This work is done 
in the Museum laboratories. 
SouTHEAST PAVILION 
INVERTEBRATES 
At the extreme east is the Darwin Hall, devoted chiefly to the 
invertebrate animals (those which do not possess a backbone) and to 
groups illustrating biological principles. Facing the entrance is a 
bronze bust of Darwin by Wm. Couper, presented by the New York 
Academy of Sciences on the occasion of the Darwin 
centenary in 1909. Passing around the hall from left to 
right the pregression is from the lowest forms of animal 
life, the one-celled Protozoa, to the highest and most complex forms of 
animal Jife, the Primates, including man. The distinctive charac- 
teristics of each group are fully described on the alcove and case labels. 
Many of the minute forms are represented by skilfully prepared models 
in glass and wax showing the animal many times enlarged. Thus 
the visitor may obtain an idea of the form and structure of these animals 
which in spite of their small size have in so many instances such a vital 
influence on the life of man. 
This alcove contains the lowest forms of animal life. All are single- 
celled individuals. The simplest kinds are abundant in swamps and 
stagnant water, others are found in myriads in the sea, 
while the ocean bottom in many localities is covered 
with them. The exhibits in this alcove are mainly models, 
some of which represent Protozoa enlarged more than a thousand diame- 
ters. 
Sponges are principally of two kinds—those with skeletons or 
supporting structures of silica (i. e., flint) and those with 
skeletons of horny fiber. The sponges of commerce belong 
to the latter class. In the dry specimens exhibited the 
skeleton only can be seen, the living tissue having been removed. Many 
of the “‘glass”’ sponges are very beautiful in design. Sponges range in 
Synoptic 
Series 
Alcove I 
Protozoa 
Alcove 2 
Sponges 
