DEPARTMENT OF MARINE BIOLOGY. 



149 



developed from several planulse. A consideration of the location of the tiles 

 in the live-car shows that each of the three tiles in the anterior row of the 

 five cross-rows bore one or more colonies ; one tile in the second row, the one 

 on the left side, bore 4 colonies ; and one tile, the one on the right side, in the 

 third row, bore 7 colonies. All colonies in the fourth row died. In the fifth 

 row the polyps attached in one culture died ; the specimens of Agaricia and 

 Favia cemented to a tile all died, though it is known that the environment of 

 the live-car is favorable for Favia. The bases of two specimens of Pontes 

 astreoides cemented to a tile were half dead in January, according to Dr. 

 Mayer, but subsequently regenerated and grew rapidly. The sinking of the 

 live-car probably brought about the death of the colonies near its rear end 

 and on the left side forward beyond the middle. 



When I examined the car in June of this year it was overgrown, inside 

 and outside, by seaweeds of several species ; there were also sponges, several 

 species of mollusks, Ostrea and Avicula, and stalked barnacles, Lepas. The 

 surfaces of the tiles were largely covered by these organisms, which often 

 concealed the young corals and probably would ultimately have smothered 

 them. Two water-buckets full of these overspreading organisms were re- 

 moved from the car and specimens were preserved for future identification. 

 This experiment has clearly proved that one factor determining the success of 

 competing organisms is growth-rate. In locations where corals might grow 

 rapidly they are smothered by other organisms that have a more rapid growth- 

 rate. This subject will be subsequently reverted to in discussing other ex- 

 periments and observations. 



The following table gives the measurements of the colonies that sur^dved 

 in the live-car experiment: 



Dimensions of corals surviving, June 1911, from planula cultures placed in floating 

 live-car in June 1910, the colonies being one year old in June 1911. 



* Fission in process. 



X See plate 4, fig. 2. 



t See plate 4, fig. i. 



In three instances — cultures i, 8, and 24 — there were adventitious speci- 

 mens, in each case Favia fragum. An inspection of the table shows a great 

 range in the size of colonies i year old. This variation may be largely ex- 

 plained by whether or no the young colony was more or less smothered by 

 algae or other overspreading organisms. The tiles in cultures 4, 6, and much 

 of 24 were overgrown with sea-weed. Specimen h of culture 24 was proba- 

 bly formed by the fusion of colonies from 6 planulse, attached on the periph- 

 ery of the tile and not so shadowed or overgrown as the other colonies. 



