No: 3:] DEVELOPMENT OF MARINE SPONGES. 325 
Collecting and Embryological Methods.— During August, 
September, and October, the Tedanias at Green Turtle Cay 
were found to contain large numbers of embryos which turned 
out to be gemmules, the development of which is essentially 
like those of Esperella. The embryos were imbedded in the 
mesoderm, but though they were abundant, they were not 
sufficiently so to cause any breaking down of the sponge tissue. 
The mesoderm of Tedania B. is a bright red and the gemmule 
embryos which were present in many stages were of the same 
color. If a Tedania is put in an aquarium, almost at once 
ciliated larvae begin to be cast out of the oscula. For the 
purpose of obtaining embryos, I found it was useless to keep 
the adult sponge more than two or three hours. During that 
time they throw out a good many embryos, but afterwards 
scarcely any. By changing the water frequently, large as 
the adults were, I could keep them alive for many hours, but 
after the first couple of hours they, like so many other marine 
animals, lose their irritability, and eject no more embryos. In 
_order to get a great number of embryos it was therefore neces- 
sary to collect many adults, keeping each of them but a short 
while. In bringing a large sponge like Tedania B. from the 
collecting grounds to the laboratory, care should be taken to 
supply it with an abundance of water, and if it must be lifted 
out of the water, let the exposure to the air be as short as 
possible. It will be found well to support the sponge with one 
hand just below the surface of the water, and with the other 
dip a bucket beneath it. In this way a sponge may be brought 
into an aquarium without having been out of the water for a 
moment. It being a matter of considerable time and labor to 
bring so many sponges from the collecting grounds to the 
laboratory in a small sail boat, I tried on a few occasions 
getting my larvae directly on the grounds. Paddling along the 
mangroves at the head of “ Black Sound,” whenever we saw a 
good sponge, my negro boy or I would fish it up and carefully 
bring it into one of the two large tubs I kept full of water in 
the bottom of the boat. When we had pretty well filled one 
of the tubs, I would wait fifteen minutes and then transfer all 
the sponges to the other tub, and begin examining the water 
