DEPARTMENT OF MARINE BIOLOGY. 159 



more than 30,000 specimens were secured from over 50 localities. On the 

 basis of personal collections and observations, proof has been obtained that 

 collective and individual evolutionary changes have taken place in the 

 Moorean species of Partula even in the brief interval from 1907 to the present 

 time. A number of new mutations has been added to the list of those found 

 earlier. Finally, in a remote area of interior forest, a new species was found 

 which is closely similar to certain forms of the island of Raiatea, more than 

 100 miles distant; this discovery strongly supports the contention that a 

 large land-mass formerly existed in southern Polynesia. The abundant 

 material is now in process of qualitative and quantitative analysis. 



Studies on the Composition of Sea-Water, by Charles B. Lipman. 



The investigations of the past year on the composition of sea-water have 

 been continued, although progress has been slow. The difficulty of obtaining 

 expert analytical assistance in this study prevents the possibility of turning 

 out a great amount of work, but the analytical work is going forward and 

 during the past year samples of sea-water from certain parts of the Oregon and 

 California coast have been analyzed. The gradually accumulating evidence 

 is substantiating the conclusion reached on the basis of earlier analyses to 

 the effect that sea-water is a much more variable substance in its chemical 

 composition than has hitherto been appreciated. Moreover, it is becoming 

 evident from the analytical results thus far obtained that some of the im- 

 portant constituents of sea-water which have never been determined (or if 

 determined, never reported) may prove to be of very great significance in our 

 physiological studies, both as regards marine plants and marine animals. 



A detailed statement with regard to these studies on the composition 

 of sea-water may be possible within a year or more. 



Observations upon Submarine Color Photography, the Food and Rate of Diges- 

 tion of Fishes, and the Power of Discrimination and Association in the 

 Gray Snapper, by W. H. Longley. 



My stay at Tortugas from June 6 to August 25 and the excellence of the 

 arrangements in the interest of my research make it possible to report 

 progress in several lines of inquiry. 



First, it appears that within certain limits submarine color photography 

 may be undertaken successfully. This has been demonstrated by securing 

 autochromes of corals, sea-anemones, sedentary worms, etc. The sole restric- 

 tion in the application of the process to work in shallow water of clear tropical 

 seas lies in the fact that an exposure of 10 to 12 seconds is necessary, a period 

 during which few animals that are not both sedentary and rather rigid remain 

 unmoved by wave or tide and undisturbed by the photographer's prepara- 

 tions. But even with this limitation, use of color photography in reef studies 

 will doubtless permit more apt representation of the general appearance of 

 submerged portions of the reef than will any method hitherto applied. 



Besides color photographs, which will serve to define some of the more 

 striking color notes in the environment of Tortugas fishes, others were secured 

 portraying species, or facts in behavior of species, of which no record had been 

 obtained earlier. That part of the work which deals with the coloration and 

 habits of Tortugas fishes may now, therefore, be prepared for publication. 



In addition to making miscellaneous observations upon the habits of 

 fishes, special note was taken of the reaction of a number of species to the 

 palolo worms available to them in myriads for a few hours on July 7 in their 



