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CARNEGIE INSTITUTION OF WASHINGTON 
very real need for additional systematic study of the group still exists. 
It seemed good, therefore, to undertake it now, since the season’s dredging 
for other purposes yielded incidentally an abundance of sponges from 
depths ranging from 15 to more than 1000 m. 
The dredged specimens were often studied while still alive and usually 
before post morten changes had set in. There numbers were supplemented 
by material collected with sponge-hook or diving-hood, or by hand from 
the reef at low tide. Over 80 species in all were obtained. Examples of 
each, preserved in alcohol, are being deposited in the U. S. National 
Museum, accompanied in many instances by representative series of dry 
specimens. Microscopic preparations of each were also made, with descrip¬ 
tive notes, and notes upon the ecology of the species where possible. 
Nitrogen in Echinoid Ontogeny, by Frederick Ronald Hayes 
After the penetration of a spermatozoon, the developing egg receives 
nothing from the outside except water and sometimes salts, until the com¬ 
paratively advanced embryo begins to eat. The morphological phenomena 
of ontogeny—intra-cellular reorganization, cell division, gross changes in 
size and shape—can be brought about only by the expenditure of energy, 
and this energy must come from materials in the egg at the time of 
fertilization. The problems of chemical embryology include (a) a deter¬ 
mination of the amount of energy required to produce these structural 
changes—the overhead expenses of development; and (b) an investigation 
of the chemical transformations taking place. Using sea-urchin eggs as 
material, the former problem received attention some years ago from War¬ 
burg and others. Oxygen requirements, carbon dioxide output, and heat 
production at various stages, suggested that the same material was not 
being burned to provide energy at all times. Virtually nothing has been 
done, however, which throws light on the chemical changes during inverte¬ 
brate egg development. This therefore seemed a suitable field for a pre¬ 
liminary investigation at Tortugas, with the sea-urchin ( Echinometra 
lucunter) as material. 
There are two sources of energy available in the egg—proteins and lipins. 
(Probably the very small quantities of carbohydrate present can be neg¬ 
lected.) In the time available, an attempt to make a general survey of the 
changes in these two classes of material would necessarily have been 
unsatisfactory. It was therefore decided so to limit the scope of the work 
that a clear-cut result might be anticipated. 
Primary amino groups were found to account for nearly 40 per cent of 
the nitrogen in Echinometra eggs. Now -NIL nitrogen is known to change 
in many metabolic processes, particularly with respect to its relation to 
=NH and s=N nitrogen. A study of the variation in the ratio 
—NFL nitrogen 
"trdanTt rooerr" during the 24 hours of development was made, for 
the purpose of gaining some idea whether profound protein transforma¬ 
tions accompany cleavage, hatching and gastrulation. Koch’s modification 
of van Slyke’s micro-apparatus was used for the estimation of —NH 2 
groups; and micro Kjeldahl tests mere made for total nitrogen. The re¬ 
sults showed that, although there may be small variations, no major change 
occurs in the ratio investigated. From this it may be suspected that there 
is probably little change in the protein during the early stages, although a 
quantitative estimation of the several amino acids present would be neces¬ 
sary before a definite conclusion could be reached. It might be further 
TORTUGAS LABORATORY 
285 
reasoned that since chemical changes of some sort almost certainly form a 
part of development, it would be profitable to make a study of the lipins. 
Some preliminary observations were made of the size changes during the 
first 24 hours. Measurements of diameters showed that the egg within the 
shell (or fertilization membrane) decreased in size until hatching time (6 
to 7 hours), following which there was a period of rapid growth. The 
diameter of an egg is 85 to 90/x. Progress was made toward the elaboration 
of a method by which these small eggs may be weighed. Weighing is more 
desirable than diameter measurement for purposes of volume estimation, 
because with the latter method one must assume that eggs are spherical, 
which is not usually true. 
Water Exchanges of Cells, by James L. Leitch 
The object of the summer’s work was to study the whole process of water 
exchange between ova of suitable types, particularly those of several 
echinoderms, and hypo- and hypertonic sea-water solutions. The program 
included the collection of samples for subsequent analysis and the measure¬ 
ment of the diameter of the eggs placed in anisotonic sea-water solutions. 
These measurements were made either by means of a filar ocular microm¬ 
eter or by photographing the eggs and measuring the negatives. In all, some 
320 photographs were taken which will be measured and the resulting data 
calculated during the coming year. 
The ova of Tripneustes esculentus, Lytechinus variegatus and Centrech- 
inus antillarum were not found in sufficient abundance or in proper condi¬ 
tion for use. 
The eggs of Echinometra lucunter, which was obtained in great number 
from Bird Key Reef, were used in the majority of the experiments. The 
eggs were obtained free from contamination by sperm or fluids from the 
coelom or digestive tract by washing the animals in tap-water and then 
inverting them in a dish of sea-water. The animals spawned within 15 
minutes. Photographic records of the volume changes when eggs were 
transferred from 100 per cent sea-water to 50 per cent and vice versa were 
made. From these photographs, studies will be made of: (1) The kinetics 
of the process of water exchanges; (2) the non-solvent volume of the eggs; 
(3) the effect on the non-solvent volume of keeping the eggs for 40 hours 
in the ice box; and (4) the variations in the kinetics of the volume changes 
for different samples of eggs from the same female and for samples of eggs 
from different females. 
In addition to the photographic records, samples of eggs from each 
female used in the above experiments were thoroughly washed with filtered 
sea-water and prepared for analysis after the removal of most of the sea¬ 
water by centrifuging. Samples of the eggs of 40 females were also pre¬ 
pared in this manner for the determination of the variability in their chem¬ 
ical composition. 
In preparation for future study of the reactions of eggs of animals of 
other phyla to hypo- and hypertonic sea-water solutions, a series of 56 
pairs of samples of the eggs of individual female hermit crabs, Calcinus 
tibicens, were prepared. Each pair of samples consisted of a few eggs 
placed in Rounds solution for a study of the shape of eggs at various stages 
in development, and a much larger sample for analytical study. The latter 
was prepared by washing the bunches of eggs in two changes of distilled 
water and then placing them in small vials in which they were dehydrated 
at 100° to 110° C. In the same manner, paired samples were made of the 
