216 CARNEGIE INSTITUTION OF WASHINGTON. 



with oxj'gen. In cultures in which there v/as less carbon dioxide the inhibitory 

 effect on both kinds of spermatozoa was less. In cultures made in pure sea- 

 water and into which a bubble of pure carbon dioxide was introduced, the 

 increased activity of the eupyrene spermatozoa around the bubble indicated 

 very clearly that there is a certain carbon-dioxide tension at which they reach 

 maximum activity. The reaction of the apyrene s])ermatozoa was less definite, 

 although there was not the slightest evidence that they were stimulated. 

 When a bubble of pure oxygen, however, was introduced, the eupyrene sperma- 

 tozoa were slowed down to a great extent. In this case the apyrene sperma- 

 tozoa were stimulated. The end reactions of the two kinds of spermatozoa 

 to bubbles of carbon dioxide and of oxygen presented configurations of ring 

 formation, both of which lend themselves to the same interpretation when 

 the opposite effect of the gases upon the two kinds of spermatozoa is borne 

 in mind. The writer, however, is not -willing to commit himself in this regard 

 until the effects of other gases, such as hydrogen and nitrogen, and of sub- 

 stances which raise and lower surface tension have been studied. 



That the combined activity of both kinds of spermatozoa results in the 

 production of a relatively great amount of carbon dioxide was demonstrated 

 by Dr. S. Tashiro, of the University of Chicago, by means of his biometor. 



Upon CO2 Productio7i in Tropical and in Temperate Marine Animals, 

 and upon CO^ in Sea-water, by Dr. Shiro Tashiro. 



The results obtained at the Marine Biological Laboratory at Tortugas 

 during June 20-July 30 are given under the following headings: 



I. Metabolism in ganglionated cord of the heart of the king crab 



(Limulus) at Tortugas. 

 II. Temperature coefficient of the metabolism in the nerve fibers. 



III. Further evidence for the increased CO2 production in nerve fiber 



on stimulation. 



IV. Tis.sue metabolism in the medusa Co.ssiopea. 

 V. Is there any free CO2 in sea-water? 



I. Metabolism in the Ganglionated Cord of the King Crab (Limultts polyphemus) 



AT Tortugas. 



Mayer's discovery that the death temperatures of the different species of 

 reef corals vary considerably according to the localities in which the animals 

 occur is a matter of considerable importance from both a physiological and 

 an ecological point of view. In general, he confirms Harvey's statement that 

 tropical marine animals normally live at temperatures much nearer the high- 

 temperature death-point than do northern forms. The highest temperatures 

 at which the king crab, Limulus, at Tortugas can live is not very much higher 

 than that of the northern forms, while its lower limit of activity is consider- 

 ably higher than that of the northern forms. In order to explain the mechan- 

 ism of this physiological difference, I made a series of studies of the metabolic 

 activities of the animals of both regions at various temperatures. Since I 

 have (with Mr. H. S. Adams) measured the CO2 production by the gan- 

 lionated nerve cord of the Limidus heart at Woods Hole, a similar investi- 

 gation was conducted on the tissue of the same form at Tortugas. 



By using the biometer, which measures quantities of CO2 as small as 

 0.0000001 gram, the rate of CO2 production in the ganglionated cord of the 

 Ldmidus, obtained at the Marquesas Keys, near Tortugas, was determined. 



