DEPARTMENT OF MARINE BIOLOGY. I23 



is known also from Woods Hole. He also demonstrated that Pennaria cavo- 

 lini from Naples, Mediterranean, is distinct from P. tiarella of America. Mr. 

 Wallace labored very assiduously over these studies, and it is surprising that 

 he should have found so many species in a tropical region, for it has been 

 generally assumed that the tropics are poorly endowed with littoral species of 

 Hydroidea. 



Alfred G. Mayer discovered that pulsation in Scyphomedus^e is caused by 

 the constant formation of sodium oxalate in the marginal sense-organs. This 

 sodium oxalate precipitates calcium, and thus sets free sodium chloride, which 

 acts as a nervous stimulant. Pulsation is thus due to the constant maintenance 

 of a slight excess of common salt in the sense-organs, over and above the con- 

 centration found in the surrounding sea-water. Moreover, the sea-water 

 itself is a balanced fluid neither inhibiting nor stimulating pulsation. The 

 sodium chloride of the sea-water is both a muscular and nervous stimulant, 

 but the magnesium, calcium, and potassium are inhibitors and exactly coun- 

 terbalance the effect of the sodium, producing a neutral fluid, thus permitting 

 the weak internal stimulus of a slight excess of sodium chloride produced in 

 the sense-organs to maintain the rhythmical pulsation. 



The Atlantic palolo worm swarmed at Tortugas on the mornings of July 

 10 and 19, 1908 ; the first quarter of the moon being on July 6 and the last on 

 July 19. Worms swarmed normally on July 19 out of rocks which had been 

 maintained in the tideless water of a floating live-car for 6 weeks previous to 

 the day of the swarming. 



The writing of a description of all of the Scyphomedusas of the world 

 has been completed, this being the second volume of a work upon the 

 "Medusae of the W^orld," the first volume of which is now going through the 

 press. 



PRELIMINARY REPORTS OF RESEARCHES, SEASON OF 1908. 



Preliminary Report upon the Reactions of Brittle-Stars, by R. P. Cozvles, 

 Johns Hopkins University. 



During the month of July, 1908, I was enabled to continue my study of the 

 habits of brittle-stars and starfish. Several species of each group were used 

 and these were studied with reference to their reactions to light and contact 

 stimuli. Special attention was paid to the influence of these stimuli, and to 

 the effect of injury on the righting reaction, for the purpose of finding out if 

 possible what it is that determines the manner of righting ; and whether there 

 is a tendency for individuals to right themselves on special pairs of rays. 

 Many series of experiments were undertaken, but I wish to continue the work 

 before drawing any definite conclusions from them. 



I also began a study of regeneration in A pi opus mayeri for the purpose of 

 determining what effect the amount of injury has on the rate of regeneration. 

 These experiments are still in progress. 



