642 



SCIENCE 



[N. S. Vol. LI. No. 1330 



of ethylene is passed into sulphuryl chloride 

 at room temperature no apparent change oc- 

 curs until the gas has bubbled through for 

 quite a long while. Under certain conditions, 

 however, the colorless liquid suddenly turns 

 gTeenish-yellow, accompanied by rather a 

 sharp rise in temperature, which during the 

 first two or three hours of the run amounts 

 on the average to approximately 10° 0. As 

 the temx)erature rises, the liquid loses its 

 color, soon to be followed by a gradual fall 

 in temperature, which in the course of a few 

 minutes reaches approximately that of the 

 room. When the gas is passed steadily 

 through the liquid, this remarkable cycle re- 

 turns again and again uniformly and con- 

 tinually in the same order. At the minimum 

 temperature the liquid invariably turns green- 

 ish-yellow (about the color of chlorine), which 

 is a sure signal that the temperature will rise. 

 At the maximum temperature, which is 

 usually in the neighborhood of 35° to 40°, the 

 liquid is colorless. A complete cycle ordi- 

 narily requires from 10 to 20 minutes, de- 

 pending upon conditions, and these cycles 

 may be observed for several hours. In the 

 course of time, however, the cycles become 

 longer and the differences in temperature less 

 pronounced. This is what one would expect. 

 A number of different runs has been made, 

 with the same general results. The accom- 

 panying diagram shows very clearly some of 

 the cycles observed when one of the experi- 

 ments was carried out. An explanation of 

 this interesting phenomenon has not been fully 

 worked out, but the mechanism of the reaction 

 is under investigation. It appears that sulphur 

 dioxide and ethylene chloride (Dutch liquid) 

 are among the products of the reaction. It 

 may be that ethylene and sulphuryl chloride 

 first unite to form an tmstable compound 

 which then dissociates into ethylene chloride 

 and sulphur dioxide, or it may be that these 

 products are formed by the interaction of the 

 factors as represented by the following chem- 

 ical equation : 



SO=C!L: -t- C,H, -» OACL -f- SO, 



William Foster 

 Princeton Universitt 



THE AMERICAN PHILOSOPHICAL SO- 

 CIETY. IV 



SATDEDAY, APRIL 24 



Afternoon Session — S o'clock 



William B. Scott, D.Sc, LL.D., president, in the 



chair 



Presentation of a portrait of the late Edward 0. 



Piokering, LL.D., vice-president of the society, 



1909-1917, by Vice-president Hale. 



Animal luminescence and stimulation: B. New- 

 ton Harvey, Ph.D., professor of physiology, 

 Princeton University. (Introduced by Dr. H. H. 

 Donaldson.) The production of light by animals 

 is due to the burning or oxidation of a substance 

 oailled luciferin in the presence of an enzyme or 

 catalyst called luciferase. It resembles the ordi- 

 nary artificial methods of iHumination by burning 

 in that oxygen is as necessary for animal lumines- 

 cence as it is for the light of a lajmp or tallow 

 candle. It differs in that water is absolutely es- 

 sential for the light production and no carbon di- 

 oxide or heat is produced — at least no carbon di- 

 oxide or heat is produced at all comparable to 

 that formed during the burning of such substances 

 as tallow, either in the form of a candle or as food, 

 to supply heat and energy for the body. Light 

 production by animals differs also from light pro- 

 duced by combustion in that the oxidation product 

 of luciferin, oxyiluciferin, can be easily reduced to 

 luciferin, which will again oxidize with light pro- 

 duction. The reaction is reversible and appears to 

 be of this nature — ^luciferin + ?:i oxyluoif erin -|- 

 HjO. The difference between luciferin and oxy- 

 luciferin lies probably in this, that the luciferin 

 possesses two atoms of hydrogen which is removed 

 to form HjO when the luciferin is oxidized. The 

 Hj must be added to reform luciferin. Whether 

 the reaction goes in one direction or to the other 

 depends, among other things, on the concentration 

 of oxygen and the presence of a reducing agent. 

 In a mixture of luciferin, luciferase, reducing 

 agent and an abundant supply of oxygen, the re- 

 action goes from left to right (with production of 

 light) to an equilibrium. On removal of oxygen 

 the reaction goes in the right to left direction with 

 reformation of luciferin. Thus, while a firefly is 

 flashing, oxyluciferiu is produced and between the 

 flashes oxyluciferin is reduced and is now ready to 

 be again oxidized with light production. We may 

 figuratively describe the firefly as a most extra- 

 ordinary kind of lamp which is able to make its oil 

 from the products of its own combustion. Not only 



