50 ZOOLOGY. 
View oF THE CLASSIFICATION OF THE PORIFERA. 
Carneospongia. 
(Spongi.) 
Calei 
(Sycon.) 
— 
= a 
PoriFERA. 
Laboratory Work.—Sponges are difficult to preserve alive in aquaria 
for study. Fine microscopic sections of the living sponge may be made 
with the razor or the microtome, and the tissues and eggs as well as the 
young be studied, though, from their minuteness, the study of the 
young is very difficult. The ciliated young of Sycon ciliatum may be 
obtained in the spring and summer by picking a portion of the sponge 
to pieces and tearing out small fragments with fine needles, until por- 
tions are small enough to be examined under high powers of the micro- 
scope. Researches on the finer structure and mode of growth of the 
sponge are difficult, and require much skill and long training in his. 
tological methods. The gross structure of sponges may be studied by 
cross and longitudinal sections made with a razor or knife. 
LITERATURE. 
Haeckel. Die Kalkschwimme. 8 vols. 1872. 
Schmidt. Die Spongienfauna des Atlantischen Gebietes. 1870. 
Schultze. Untersuchungen ueber den Bau und den Entwicklung 
der Spongien. (Zeitschrift fiir wissens. Zoologie, Bd. 25-35. 1876- 
1881. 
Hyatt. Revision of the North American Porifers. (Memoirs Bos- 
ton Soc. Nat. Hist., ii. 1875-1877.) 
Vasmaer. Porifera, in Bronn’s Klassen und Orduungen des Thier- 
reichs. 1882. Also the treatises of Bowerbank, Clark, Lendenfeld, 
etc. 
