206 CARNEGIE INSTITUTION OF WASHINGTON. 



When increasingly stale and tested eggs were fertilized by increasingly 

 stale sperm there was no additional change; the results are altogether like those 

 obtained with stale eggs by fresh sperm. 



A number of experiments were also made with a view to finding out the 

 nature of the factors that gave rise to these changes, with particular emphasis 

 upon the influence of the alkalis in sea-water and of the calcium content. 

 These will be described in full elsewhere. 



The CO2 Factor in the Regeneration of Cassiopea xamachana, 

 by A. J. Goldfarb. 



The striking resemblance between the curve for the rate of nerve conduction 

 in Cassiopea when CO2 is present in the distilled water used to dilute the sea- 

 water, and the curves obtained by the writer in the regeneration of the same 

 organism when placed in different concentrations of sea-water suggested the 

 possibility that the supernormal regeneration in diluted sea-water may not 

 only be due to changes in salinity, but also to differences in the amount of 

 CO2 added with the distilled water. If this were found to be the case, the 

 resemblance would have considerable significance. 



To test this hypothesis, sea-water was diluted with the same water (rain- 

 water) used in previous experiments. In a second series distilled water was 

 used, from which nearly all the CO2 had been removed. Inasmuch as there 

 was still a trace of CO2 in excess of sea-water in both these waters (the exact 

 amount of which was determined), sufficient NaOH was added to neutralize 

 the free acid in the solution. In another series more NaOH was added, not 

 only to neutralize all the free acid, but some of the acid (CO2) given off by the 

 pulsa,ting organisms during the next 24 hours. A comparison of these series 

 of experiments should have established the influences of the graded amounts 

 of CO2 in the different concentrations of sea-water upon the regenerating ani- 

 mals with their total of 640 regenerated arms. 



While each series of experiments differed in certain details from the other 

 series, yet there was no significant difference. All showed the same rise in 

 the curve between 100 per cent and 80 per cent sea- water, as in the experiments 

 of 1914. 



The experiments made known many complicating factors not heretofore 

 suspected, which factors need further study. So that it seems inadvisable at 

 the present stage of the inquiry to make any definite conclusions. 



The Fishes of Southern Florida, by E. W. Gudger. 



SHARKS. 



During the two and a half weeks spent at Key West, with a gasoline launch 

 at my command, I had expected to have no trouble in getting sharks as hereto- 

 fore, i. e., by going around to the city abattoir, selecting the shark, harpooning 

 it, and towing it to my working-quarters for description, measurement, and 

 dissection. However, it was found that almost nothing in the form of bait 

 was being thrown overboard at the slaughter-house, and that no sharks had 

 been seen for weeks. In fact, but one shark was gotten there, and that was 

 caught by some boys and kept for me. In this dilemma, I resorted to hook- 

 fishing, with the services of the best fisherman in Key West. Here but indif- 

 ferent success was had ; two fish a day were caught when any were taken, but 

 there were many barren days. However, six large sharks were caught, and 

 were carefully described, measured, and dissected. Nearly all were females, 

 but unfortunately none were breeding. However, careful notes were made 

 of the structures of the reproductive organs, with a view to eventually working 



