144 



SCIENCE 



[N. S. Vol. XLIII. No. 1100 



without eorreetions for the difference in the 

 energy of these regions. They are, however, of 

 such a nature that the corrections mentioned will 

 not result in marked alterations. 



For all but one of the microscopic organisms 

 the results fall into two groups. In the one 

 group the region of stimulation begins in the blue 

 near the violet, between 430 ii/j. and 440 iif- From 

 here toward the red end of the spectrum the stim- 

 ulating efficiency rises, at first slowly and then 

 rapidly, to a maximum in the green near the yel- 

 low, between 530 /x/t and 540,ufi; then it falls, at 

 first rapidly and later more and more slowly, end- 

 ing in the red at about 640 /i^. In the other 

 group the region of stimulation begins in the violet 

 between 420 /i/i and 430 /i^u, only a short distanr^e 

 from the place where it begins in the first group. 

 From here the efficiency rises very rapidly, reacU- 

 ing a maximum in the blue between 480 /ifi. and 

 490 /</i. It then falls rapidly and ends in the 

 green in the neighborhood of 520 ju/i. Three of 

 the microscopic forms, Pandorina, Eudorina and 

 Spondylomorum, belong to the first group, the rest 

 to the second. To this group belong also Areni- 

 cola larvae and the earthworms. For the remain- 

 ing microscopic form (Chlamydomonoi) the maxi- 

 mum is in the green very near 510 mm; and for the 

 blowfly larvEe it is approximately at 520 fiii. The 

 distribution in the spectrum, of stimulating effi- 

 ciency is, for this creature, essentially the same as 

 the distribution of brightness for color-blind per- 

 sons. 



These results show that stimulation in all of the 

 organisms studied depends upon the wave-length 

 of the light; that the stimulating efficiency is very 

 much higher in certain regions of the spectrum 

 than in others; but that the distribution of this in 

 the spectrum differs greatly in certain organisms 

 that are closely related in structure, e. g., Pando- 

 rina and Gonium, while it is essentially the same 

 in others that are very different in structure, e. g., 

 Euglena and earthworms. They also have a bear- 

 ing on the nature of the chemical changes associ- 

 ated with the reactions to light. 

 Negative Orientation in Vanessa Antiopa: Wm. L. 

 Dallet, Jr., Randolph-Macon College. (Intro- 

 duced by S. O. Mast.) 



Certain photo-positive insects orient, on coming 

 to rest in direct sunlight, so that they face di- 

 rectly away from the sun. Is this phenomenon de- 

 pendent upon previous violent exercises, as Pro- 

 fessor Parker holds, and is it a reaction to light 

 or to heat? 



Vanessa, which has been raised in a small cage 



and had never flown in the open, repeatedly 

 oriented negatively in sunlight, as did also speci- 

 mens with both eyes covered so that no light 

 could enter. Moreover, normal animals exposed 

 in darkness to heat-rays from an electric flatiron 

 usually face away from the source of heat, and 

 they respond in the same way even when the heat- 

 rays are opposed by light-rays coming from the op- 

 posite direction. Furthermore, when normal ani- 

 mals are placed in a room the temperature of which 

 is high (29° C. to 32° C.) they do not orient at all, 

 no matter how they are illuminated. 



These results seem to show that when Vanessa 

 faces away from the sun on coming to rest in sun- 

 light, it is reacting to heat and not to light, and 

 that this reaction is not necessarily dependent upon 

 previous violent exercise. 



Electric Currents Generated in the Eye of the 

 Fish by Light: Edwaed C. Day, Syracuse Uni- 

 versity. 



The live fish, wrapped in a wet cloth, gills irri- 

 gated by a hose led into the mouth, was placed in 

 a dark box. Electrodes were applied to the eye, 

 one to the cornea and one to back of eye-ball, and 

 connected with string galvanometer. When light 

 struck the eye the galvanometer recorded electrical 

 disturbances. By projecting the shadow of the 

 string into a photographic apparatus its deflec- 

 tions could be recorded along with time and ex- 

 posure curves. On-eflfect consists of a slight de- 

 pression A, followed by a strong abrupt elevation 

 B and another slower secondary rise C. Off-effect 

 consists of an abrupt elevation D. 



For dark-adapted eye all four deflections are 

 present; B is always greater than D. For light- 

 adapted eye A and C are absent; B is smaller than 

 D. Latent period from onset of light to begin- 

 ning of ^ = 0.032", S = 0.075", C—1-7"; and 

 from extinction of light to beginning of D = 0.05". 

 Beflections may be resultant expression of in- 

 terfering reactions of three substances in the 

 retina. 



Intermittent stimulation gives oscillatory curve 

 composed chiefly of A and D deflections; 25 flashes 

 per second evoked 25 oscillations, and oscillations 

 blended at 28 flashes per second. 



Changes in Thelia bimaculata (Fabricius) Induced 

 by Insect Parasites (illustrated with lantern) : 

 S. I. KOENHAUSEE, Northwestern University. 

 (Introduced by Wm. A. Logy.) 

 In Thelia pronotum covers entire body, extend- 

 ing far in front of head as a horn and back over 

 thorax and abdomen. It is coarsely punctured 



