94 



SCIENCE. 



THE WINGED PHYLLOXERA. 



J. S. Hyde, of Santa Rosa, California, a few days since, 

 while examining some grape-vine roots infested with the 

 phylloxera remarked to some friends present that there 

 was little danger of a rapid spread of this pest, as the 

 insect, in its winged form, had not yet appeared. The 

 words had scarcely passed from his lips when one of the 

 gentlemen cried out : " I see one with wings now !" 

 On a more careful examination eight full-winged speci- 

 mens were tound ; the next day four other specimens 

 were discovered. Several of these insects were sent 

 to Dr. Hilgard of the Stale University for examination. 



The above announcement by Dr. Hyde is very 

 interesting, and not the less so from the fact that the 

 insects he sent to Prof. Hilgard, although truly a winged 

 form, were sterile, and not capable of spreading the 

 destruction which our vine-growers fear. In order to 



Fig. i. 



Fig. 



show the difference between the fertile and infertile 

 winge:l-forms, we have reproduced engravings from 

 Prof. Riley's drawings of the phylloxera which show 

 clearly the distinction between the two. Fig. I is the 

 fertile winged female, which thus tar has not been 

 observed in this State, unless some of the insects 

 retained by Dr. Hyde are of this form. Fig. 2 shows 

 the outline of each of the five specimens received by 

 Prof. Hilgard. It will be observed that in the fertile 

 winged female the abdomen is prolonged and that the 

 body is about half as long as the whole insect, wings 

 included, and is ol a tapering, rounded form. In the 

 sterile, the body is rarely one-third the length of the 

 whole insect, and the abdomen is abruptly contracted, 

 as shown in the engraving. 



Concerning the finding of the sterile winged form by 

 Dr. Hyde, Prof, Hilgard spoke at the meeting of the Hor- 

 ticultural Society as follows : " After all the matter still 

 rests pretty much as we conjectured two years ago. I 

 i hen stated that either the winged phylloxera was not 

 here at all, or in very small numbers. There are five or 

 six varieties of the insect non-winged, which live on the 

 and which produce a winged form towards autumn, 

 which, like the wingless form, is simply a female which 



lays eggs without any connection on the part of the male. 

 The winged female is simply an egg-layer, like the others. 

 She lays a few eggs only. Some of these eggs produce 

 males and others females. It seems to be necessary that 

 there should be a kind of renovation of the race in that 

 way. The winged insect is dangerous, of course, because 

 it is capable of flying to some extent. In Europe the 

 winged form has been known to traverse a distance ot 30 

 or 40 miles at one jump, leaving districts between unaf- 

 fected. In Sonoma the progress of the pest has been 

 slow, and it has been thought that the winged insect was 

 absent. The winged forms produce only two varieties- 

 one fertile, the other infertile. I understand that in othc 

 countries the proportion of infertile insects is small. Of 

 the eight specimens sent me by Dr. Hyde, I find that five 

 are of the infertile kind. I infer, therefore, from the evi- 

 dence thus far produced, that the spread of the pest will 

 still be comparatively slow, depending upon the kinds 

 that crawl instead of those that fly." 



The announcement of Dr. Hyde, which was made to 

 the Rural Press, will doubtless induce a still wider search 

 for the winged insect. We shall be pleased to receive any 

 specimens which may come to the eyes of our readers to 

 determine their exact standing. 



INSTANTANEOUS PHOTOGRAPHY IN A BAL- 

 LOON. 



Paul Demarets. 



Since the memorable day when the bold Pilatre de 

 Rozier and the Marquis d'Arlandes left the earth for the 

 first time, up to the present, all aerial travelers have been 

 struck with the clearness with which the celestial land- 

 scapes have opened up to their view. The idea of em- 

 ploying photography to fix these admirable contours is 

 contemporaneous, so to speak, with the invention of 

 Niepce and Daguerre. 



To M. Nadar belongs the credit of making the first 

 attempts, and to M. Dagon the merit of remarkable exe- 

 cution in bringing the ascensions under control. But in 

 spite ot these successes, thanks to the generous aerial 

 hospitality of M. Henry Giffard, one would think that the 

 fixation, at a distance, of celestial landscapes upon a 

 sensitized plate in a balloon, was a mere chimera. In 

 fact the rapidity of the motion of the aerostatic globe, and 

 the rotation about its axis, would seem insurmountable 

 obstacles. 



Attention has been recently directed to the rapidity of 

 impression which may be attained, and which I believe I 

 have increased by the aid of certain re-agents ; but one 

 difficulty still to be surmounted was the want of some 

 means by which the operculum could be closed with such 

 rapidity that the operation would take only a fraction of a 

 second. 



The readers of L ' Electricitd know how M. Stein, the 

 able experimentalist of Frankfort, sought for a solution 

 of this problem. It has also described the ingenious 

 apparatus which M. Janssen has made use of in his 

 observatory at Mendon, by which he has secured 

 great rapidity of action on burning a thread of silk which 

 held the mechanism in position. P>ut it was impossible 

 to use this apparatus in an aerostat, although admirably 

 adapted to observation from a fixed position. I should, 

 therefore, have been unable to employ this method if the 

 idea had not occurred to me of using electricity by the 

 aid of the mechanism I am about to describe. 



I take a ring, in the centre of which my objective is 

 fixed, normally and solidly, and for the sake of illus'.ra- 

 tion, we shall suppose it to be horizontal. A spring, at- 

 tached to an arc, situated at the centre and parallel with 

 the objective, presses a horizontal plate, parallel with the 

 ring of the base. This plate bears a shoulder which 

 rests upon a vertical piece of iron. This has a vertical 



