122 re;ports of investigations and projects. 



Dr. Charles R. Stockard finds that in the medusa Cassiopea xamachana the 

 rate of regeneration increases in a direct ratio to the extent of injury, in ac- 

 cordance with Zeleny's rule. Dr. Stockard also makes the interesting discov- 

 ery that the regenerating tissue grows at the expense of the normal tissues of 

 the body, so that the body shrinks in size while the regenerating parts con- 

 tinue to grow rapidly. He calls attention to the important fact that cancerous 

 growths have the same remarkable power to absorb nutriment at the expense 

 of the body as has regenerating tissue. 



Dr. Stockard also carried out numerous observations upon regeneration in 

 brittle-stars, but these did not follow Zeleny's rule, but gave indefinite results ; 

 one species behaving in a manner exactly contrary to Zeleny's rule and the 

 other being indifferent to it. Dr. Stockard finds that the arms regenerate 

 more rapidly the nearer the cut is made to the central disk. Both the medusa 

 and the brittle-star thus support Morgan's law that the deeper the level of the 

 cut the more rapid the regeneration. 



Dr. T. Wayland Vaughan finds that there are at least four types among the 

 Florida Keys. 



(i) North of and including Key Biscayne the keys are made of silicious 

 sand with some comminuted shells. 



(2) From Soldiers Key to the southern end of Big Pine Key the islands 

 are composed mainly of elevated reef rock. 



(3) West of Bahia Honda the keys are composed chiefly of an oolitic lime- 

 stone. 



(4) The Tortugas are composed of comminuted shells and corals, some- 

 times considerably indurated. 



Dr. Vaughan finds that traces of silicious sand extend downward along the 

 Bay of Florida side of the keys to Long Key. He is of the opinion that the 

 Florida oolite has been found in a water-laid deposit probably behind a sea- 

 ward barrier. He studied the formation of the mangrove shoals behind the 

 keys, and shows that the powerful tidal currents which pass through the open- 

 ings between the outer keys cause these shoals to trend in a direction perpen- 

 dicular to the line of the barrier keys themselves. The shoals form in regions 

 of still water along the sides of currents. 



Dr. Vaughan is rearing reef corals from the young at Tortugas, and finds 

 that the planulae may remain afloat for 12 days, thus rendering it possible for 

 them to be carried 800 miles in the Gulf Stream. He is also making a study 

 of the growth of corals found naturally upon the reefs, and is conducting 

 observations upon the environmental factors, associations, etc., of the reef 

 corals. His plan of study is far more detailed, and consequently more accu- 

 rate than any that has hitherto been attempted. 



Mr. W. Seward Wallace collected and studied about 50 species of hydroids 

 at Tortugas. Among them he found the hydroid of Zanclea gcmmosa, which 



