150 



REPORTS ON INVESTIGATIONS AND PROJECTS. 



PLANULA CULTURES PLANTED ON STAKES OFF FORT JEFFERSON MOAT-WALL. 



Eight tiles bearing polyps of Pontes astreoides, derived from planulse that 

 attached in the aquarium, were planted off the northwest face of the Fort 

 Jefferson moat-wall. The following table gives the record of these experi- 

 ments : 



Record of culture tiles planted oif Fort Jefferson moat-wall. 



In 1910 attention was called to the variation in frequency of attachment of 

 planulae of respectively different parents. This experiment indicates that, 

 once attached, the planulae of different parentage have about equal chances of 

 surviving. Planting the tiles directly in the ocean gave proportionately bet- 

 ter results than planting in a floating live-car. In the live-car 160 planulae 

 gave 17 colonies, representing 46 planulae (about 20 on culture 4 were origi- 

 nally in a cluster), while on the stakes 43 planulae produced 11 colonies, 

 representing 14 planulae. The death of many of the young corals in the live- 

 car was probably due to its sinking and to the hurricane. The tiles on the 

 stakes suffered some, but not greatly, from the hurricane ; considerable silt 

 and sand settled on the upper surfaces. The following table gives the dimen- 

 sions of these colonies : 



Dimensions of Porites astreoides colonies stirviving from planula cultures planted on 

 stakes, showing the grozvth attained at the end of the first year of their lives. 



* See plate 4, fig. 3. 



Of the culture-tiles that bore colonies in 191 1, Nos. 8 and 24 were planted 

 on stakes driven into the reef off the northwest face of Loggerhead, while 

 all of the others were planted on stakes off the northwest face of the Fort 

 Jefferson moat-wall. These colonies constitute a definite basis for the study 

 of the growth-rate of the species represented and of the influence of environ- 

 ment on variation. These experiments and observations are being supple- 

 mented in several ways, accounts of which follow. 



