18 PORIFERA. 



Lankester: A Treatise on Zoology, Porifera, and Coelenterata, Pt. 2, 1900. 

 Moore: A Practical Method of Sponge Culture. Bui. U. S. Bur. Fish., 28, 



1908. 

 : The Commercial Sponges and the Sponge Fisheries. Bui. U. S. Bur. 



Fish., 1908. 

 Parker: The Reactions of Sponges, with a consideration of the Origin of the 



Nervous System. Jour. Ex. Zool., 8, 1910. 

 H. V. Wilson: On Some Phenomena of Coalescence and Regeneration in 



Sponges. Jour. Ex. Zool., 5, 1907. 

 : Development of Sponges from Dissociated Tissue Cells. Bui. U. S. 



Bur. Fish., 30, 1910. 



GRANTIA. 



This form is quite common along the New England coast, 

 where it occurs attached to rocks, seaweeds, and submerged 

 woodwork from just below the lowest tide-mark to a number of 

 fathoms in depth. You should visit an old wharf where speci- 

 mens may be found, and study their relation to the forms with 

 which they are associated. Specimens will be found to vary 

 considerably in size. The largest sometimes reach an inch in 

 length. 



1. Examine a dry specimen and notice its general shape, 

 manner of attachment, and osculum. The osculum is surrounded 

 by a funnel of rather long spicules. Distributed over the gen- 

 eral surface, more or less hidden by the numerous spicules, are 

 many small pores. Their presence may be demonstrated more 

 satisfactorily later. 



2. Look for indications of budding. If your specimen does 

 not show this, examine others. 



Make an enlarged drawing of a sponge. 



With a razor or sharp scalpel cut a dry specimen into halves, 

 with a stroke from base to osculum, and notice: 



3. The central cavity or cloaca. 



4. Many apopyles, the inner openings of tubes that are em- 

 bedded in the walls of the sponge, will be seen opening into 

 the cloaca. Are the apopyles arranged in any order? 



5. With the low power of your microscope (with the light 

 turned off) examine the cut wall and find that it is traversed by 

 parallel tubes. Determine that these tubes are of two kinds. 



