November 6, 1914] 



SCIENCE 



681 



hours, the ultraviolet light still caused mem- 

 brane formation. This effect of the ultra- 

 violet rays was not prevented by even an ex- 

 cessive quantity of NaCN, v^hich inhibits oxi- 

 dation in the egg. The membrane formation 

 under the influence of ultraviolet light took 

 place in neutral solutions as well as in weakly 

 alkaline ones. 



The calling forth of the membrane forma- 

 tion was due to a direct action of the ultra- 

 violet rays upon the egg and not to a product 

 formed by the rays in the sea water or in the 

 air. For sea water which had been exposed 

 to the influence of the rays, no matter how 

 long, without containing eggs, did not cause 

 membrane formation when the eggs were put 

 into it after the ultraviolet light was 

 turned off. 



These experiments show that causation of 

 membrane formation in the unfertilized sea 

 urchin egg and the subsequent inducement to 

 development were due to the direct effect upon 

 the egg of ultraviolet waves below 2607 A. u., 

 since, according to Dr. and Madame V. Henri, 

 waves below this range can not penetrate a cover 

 glass of 0.14 mm. thickness. It is not possible 

 to state in which way the ultraviolet waves 

 caused the membrane formation in the egg 

 except that it could take place without free 

 oxygen as well as in the presence of NaCN. 



The results mentioned thus far were ob- 

 tained in the egg of the sea urchin. The egg 

 of CTuetopterus, after an exposure of from five 

 to ten minutes to the ultraviolet rays under 

 the conditions mentioned above, developed 

 into swimming larvffi, without cell division. 



Since Eontgen rays are only very short light 

 waves, and since they also cause cytolysis, they 

 should also cause membrane formation of the 

 unfertilized egg. It is of interest that G. Bohn 

 states that Eontgen rays induce artificial par- 

 thenogenesis. His experiments were made be- 

 fore the role of the membrane formation (or 

 the alteration of the surface of the egg) was 

 recognized as a necessary step in development, 

 and he therefore does not mention whether or 

 not Eontgen rays induce membrane formation. 

 Jacques Loeb 



The Eockepeller Institute for 

 Medical Eeseaech, New York 



ON THE FEASIBILITY OF DETERMINING EXPERI- 

 MENTALLY THE LUNAR AND SOLAR DEFLEC- 

 TION OF THE VERTICAL BY MEANS OF 

 TWO CONNECTED WATER TANKS 



For some time I have had in mind the 

 essentials of the arrangement or apparatus 

 described below, the purpose of which is to 

 ascertain the deflection of the vertical as dis- 

 turbed from its mean position by the attraction 

 of the moon and sun. It may not be new; 

 but I have never seen it described or referred 

 to elsewhere. 



Briefly described, such apparatus would con- 

 sist of two tanks or cisterns of equal diameters 

 and of equal depths, located some distance 

 apart, upon the same level, and connected by 

 means of a pipe. This pipe should be of metal 

 excepting for some distance near its central 

 portion where a glass section or length of 

 much smaller diameter should be inserted. 

 The pipe should be attached to the bottoms 

 of the tanks in order to avoid complications 

 which would otherwise arise should the tem- 

 peratures of the water in the two tanks become 

 somewhat unequal. But if the pipes are 

 attached to the bottoms of the tanks, the 

 unequal expansion of the water wiU not seri- 

 ously affect the equilibrium and so will not 

 set up any flow of consequence from one tank 

 to the other. 



At any given place upon the earth's surface 

 the direction of the instantaneous vertical 

 continually deviates from its mean position 

 by a small angle dependent upon the time (or 

 local hour angle) selected and the positions of 

 the moon and sun relative to the earth's center. 



Ignoring the attraction of the disturbed 

 oceans, the plumbline upon an unyielding 

 earth deviates in accordance with the im- 

 pressed horizontal forces. These forces, in 

 terms of g or terrestrial gravity are: 



Eastward force, 

 = —0.0000001684 cos XCM^ sia (m^i + arg» M^) 

 -1- S, sin (Sjt + argo SO + • ■ • ]• 

 — 0.0000001684 sin \[Ki sin (k^t -f aTg„ Kj) 

 -(- Oj sin (Oi* -|- argo Oi) 



P,sin(p,*-t-arg„P,) + ...]. 



Southward force, 

 = 0.0000001684 cos X sin XEMj cos (ma* -(-' argo M^) 

 + Sj, cos (s^t + argo S^) -1- • ■ • ]. 



