4o6 



THE POPULAR SCIENCE MONTHLY. 



describes the instruments used for this 

 research, and the manner in which they 

 were employed. His conclusion is that, in- 

 asmuch as he failed to see in the corona 

 spectrum the dark lines of the sun's spec- 

 trum, therefore the light of the corona is 

 not all reflected light. The considerations 

 which confirm him in this conclusion he 

 states as follows : " Until this eclipse no 

 observer has ever seen the dark lines in the 

 spectrum of the corona except M. Janssen^ 

 who reported dark lines, notably D in 18*71, 

 but much more difficult to see than the 

 bright lines. Several observers during the 

 recent eclipse failed to see the dark lines, 

 though they looked for them carefully. 

 While I do not question the results of ob- 

 servers who report the presence of dark 

 lines, I think all the observations taken to- 

 gether show that the continuous spectrum 

 of the corona is not the spectrum of the 

 sun. Aside from this, Prof. Arthur W. 

 Wright made measurements of the polari- 

 zation of the light of the corona, the first 

 time, I think, it has been attempted, aad 

 has found the polarization to be but a small 

 percentage of the whole Hght emitted. Al- 

 though all reflected light does not reach us 

 as polarized light, yet I think the small per- 

 centage of polarization, taken with the faint- 

 ness of the dark lines, indicates that the co- 

 rona is, to a considerable extent, self-lumi- 

 nous. The meteoric dust not only reflects 

 the sun's light, but it is continually shower- 

 ing upon the sun, and in its passage through 

 the atmosphere is rendered incandescent." 



Investigating the Cotton-Worm.— Prof 



A. R. Grote is at present visiting the cotton- 

 growing States for the purpose of studying 

 there the habits of the cotton-worm, and 

 more particularly of determining whether 

 the fly from which it comes is acclimated 

 in those States, or whether it is annually 

 imported. The latter opinion, as our read- 

 ers are aware, is the one held by Prof 

 Grote, and it appears to be confirmed by 

 this later investigation. According to his 

 theory, the fly comes from the West Indies 

 with the south winds every year. Having 

 reached our cotton-producing States it there 

 raises its first brood. The eggs are depos- 

 ited on the under side of the cotton-plant 

 leaf In about three weeks the young worm 



" webs up " and becomes a black chrysalis 

 in a thin cotton-cocoon within a fold of the 

 leaf, and in due time the perfect insect 

 emerges. This new fly, born in the South, 

 moves in a general northerly direction, and 

 in this way the country is overrun by the 

 several ensuing broods. If the worm ap- 

 pears while yet the plant is young, the 

 planter can exterminate it by the use of 

 poison ; but if it comes late it will not do 

 harm enough to warrant much expense in 

 killing it. Paris-green in a liquid form, or 

 dilute carbolic acid, kills the worm when 

 applied to the under side of the leaf as spray. 

 Care must be taken to keep these poisons 

 from the seed-cotton, and they should only 

 be employed against the first brood of worms 

 *before the bolls open. 



An Eastern Fish-Story. — A series of in- 

 teresting letters is now appearing in Land 

 and Water, entitled " Recollections of Bang- 

 kok," and in one of them a good descrip- 

 tion is given of the mode of capturing in- 

 sect prey, followed by a species of " archer 

 fishes," several specimens of which are kept 

 in a small pond in the grounds attached to 

 the palace of the " Second King '* of Siam, 

 It is much to be regretted that the author 

 neither describes these fishes nor notes any 

 particulars by which the species might be 

 determined. Our readers will find in the 

 Monthly for January, 18*78, an illustrated 

 paper on " Archer-Fishes." When the 

 writer in Land and Water came to the 

 pond its finny inhabitants were found to be 

 in a high state of excitement, the cause of 

 which was soon evident. " A small branch 

 covered Avith black ants had been picked 

 by one of the attendants off one of the over- 

 hanging trees ; and, holding this a few feet 

 over the pond, volleys of minute globules 

 of water were directed at it from the mouths 

 of all the little fishes crowded underneath. 

 This was continued until all the ants were 

 knocked off into the water. Then ensued a 

 scramble for the prey. Any small insect 

 within their range met the same fate, and 

 they shot with the most unerring aim. As 

 I stood watching the curious sight, close to 

 the edge of the pond, a small fly lighted on 

 my hand, but was hardly seated before a 

 volley of watery bullets knocked him off his 

 perch, though at a range of four or five feet. 



