Mat 25, 1917] 



SCIENCE 



501 



results of some experiments which may seem 

 more significant to the writer than they would 

 to a physicist. Up to the time Bigelow and 

 Hunter's paper was published, at least, the 

 literature did not seem to cover the point at 

 all satisfactorily, yet many statements and 

 implications seem to be clear. Eamsay and 

 Shield's classic determinations of surface ten- 

 sion based upon capillary rise may be cited 

 as an example. If capillary rise is affected 

 by the nature of the tube, their results would 

 apparently be invalidated. 



Do not three substances ordinarily play 

 parts in capillarity, and does not the result 

 depend on the identity of each of the sub- 

 stances? If water, air and glass are the sub- 

 stances, the water heaps up against the glass, 

 and if the tube is of hair-like diameter there 

 is a rise of water. Is not this due to the fact 

 that where water, air and glass come together 

 molecules of water are drawn toward the glass 

 much more than toward molecules of air or 

 other molecules of water? 



The mechanics of this process seem simple, 

 whereas it is difficult to conceive how the 

 raising of the liquid can be a product of its 

 surface tension alone,* even though the walls 

 of the tube above the liquid have a contractile 

 coating of adsorbed liquid or a membranous 

 extension of the liquid in the tube. 



The writer is particularly interested in the 

 part that capillarity or differences in inter- 

 molecular attractions may play in oil and gas 

 accumulation. In the vicinity of oil and gas 

 pools which occupy the pores of rocks in the 

 earth, water with various quantities of salt in 

 solution, oil of one or more kinds, natural gas 

 and perhaps air are in contact with each other 

 and with various minerals. Oil and gas are 

 found in relatively large-pored rocks, in pools 

 which show some similarity in shape and the 

 pressure upon them is usually several hundred 

 pounds to the square inch. The pressure on 

 some pools is greater than that which would 

 be exerted by a column of water e^xtending to 

 the surface. May not these features be ex- 



4"Washburne, C. W., "The Capillary Concentra- 

 tion of Gas and Oil, ' ' Am. Inst. Min. Eng. Trans., 

 Yol. 50, p. 830, 1915. 



plained in considerable part by differences in 

 intermolecular attractions ? 



E. W. Shaw= 



SYNCHRONOUS RHYTHMIC MOVEMENTS OF 

 FALL WEB-WORM LARV^ 



Eecent discussion in Science of synchro- 

 nous actions of certain animals, notably, flash- 

 ing of fireflies, brings to mind a habit of the 

 larvse of the fall web-worm (Hyphantria 

 cunea), which seems to be of the same nature. 

 Whether it has been noted in the literature 

 or not I am unable to say; probably it has, as 

 it is of common occurrence. In any event a 

 short account of the habit may not be out of 

 place in this connection. 



Fall web-worm larvae, scattered over the 

 outside of the web, may be seen, at inter- 

 vals of from three to five minutes, to start a 

 sharp rhythmic swaying from side to side, 

 accomplished by raising the anterior half of 

 the body to a semi-erect position, then moving 

 it quickly, first to one side then to the other, 

 through an angle of about ninety degrees. 

 The movement is started by a few of the 

 larvse, but in a few seconds all the individ- 

 uals in the colony will be moving in the same 

 manner and in perfect unison. I do not have 

 my notes at hand but, as I remember it, the 

 movements were at the rate of about forty per 

 minute and continued each time for from 

 forty-five seconds to more than a minute. Even 

 more suddenly than they start, the movements 

 cease. 



What the cause is for this strange habit is 

 a piizzle. It seems to have nothing to do 

 with spinning the web. Artificial stimuli 

 failed to start them before the end of the rest- 

 ing interval although various means were 

 tried. These included sounds, both musical 

 and otherwise, made with various instruments, 

 smoke and strong chemical odors, jarring and 

 several other devices which suggested them- 

 selves at the time. Equally futile were at- 

 tempts to stop the movements. 



There seemed to be no leader, the swaying 



starting one time in one part of the colony 



or even in several parts at once, and again in 



5 Published by permission of the director, U. S. 



Geological Survey. 



