1884.] 



MICROSCOPICAL JOURNAL. 



103 



under surface of the glass-slide s. 

 Let r represent the silvered surface 

 of the glass disc, 6 the immersion 

 objective, J' the thin glass cover. It 

 will be easily seen that the ray of 

 light /i from the mirror or condenser 

 above the stage will enter the slide 

 and thence be refracted to the silvered 

 surface of the illuminator /-. whence 

 it is reflected at a corresponding an- 

 gle to the object in the focus of the 

 objective. A shield to prevent un- 

 necessary light from entering the ob- 

 jective can be made of any material 

 at hand by taking a strip one inch 

 long and three-fourths of an inch 

 wide and turning up one end. A 

 hole of not more than three-six- 

 teenths of an inch in diameter should 

 be made at the angle. The shield 

 should be placed on the upper surface 

 of the slide so that the hole will cover 

 the point where the light from the 

 mirror enters the glass. With this 

 illuminator Moller's balsam test-plate 

 is resolved with ease, with suitable 

 objectives. Diatoms mounted dry 

 are shown in a maimer far surpass- 

 ing that by the usual arrangement of 

 mirror, particularly with large angle 

 dry objectives. 



VVm. Lighton. 

 Ottumwa. la. 



The Wine Fly. 



On the fifteenth of February the 

 New- York Microscopical Society 

 held an open meeting to hear a paper 

 by Dr. Samuel Lockwood, secretary 

 of the New Jersey State Microscopi- 

 cal vSociety. His subject was the 

 Wine Fly. Drosophila ampelopJiila. 

 The paper was a contribution to the 

 life-history of this minute insect. He 

 had given in part three years to 

 its study, beginning in September, 

 iSSi, when nothing whatever of its 

 life-history seemed to have been 

 known. In October the flies at- 

 tacked his Concords. He found upon 

 a grape which he was inspecting with 

 a pocket-lens an extremely small 

 white egg, but lost it. The grapes 



when brought on the table were in- 

 fested by the flies, which proved 

 to be the above-mentioned species. 

 When driven from the grapes they 

 would fly to the window, where he 

 captured twf) of them. These were 

 placed in a jar, with a grape for food. 

 In two days he foimd one egg on the 

 outer skin of the grape. The lay- 

 ing was kept up for four or five days, 

 until there were about thirty, some on 

 the outside of the grape and some at 

 an opening where the two flies had 

 fed. The egg had a pair of curious 

 suspenders near the end where the 

 mouth of the larva would develop. 

 These suspenders were attached at 

 their ends to the grape, but where the 

 egg was laid in the soft part of the 

 fruit the suspenders were spread out 

 at the surftice ; thus the larva would 

 emerge clean from the shell. The 

 egg was 0.5 mm. in length, and 

 about a fourth of that in width. The 

 lai"va when grown was at least four 

 times as long as the ^%%- As the 

 larva burrowed in the juices of the 

 fruit two quite prominent breathing 

 tubes at the posterior end were kept 

 in the air. Betvv^eeen these cardinal 

 tubes were several teat-like points, 

 much smaller, but having a similar 

 function. 



The larvae appeared in five days 

 after the eggs were laid. In about 

 as many more days the puparium 

 state would be entered, and in about 

 six days more the fly or imago would 

 appear. In ovipositing the suspen- 

 sors would leave the ovi porous duct 

 last. The paper claimed that the 

 curious shape of the c^^ compelled 

 the female to oviposit slowly, as it 

 took time for the g^^ to assume its 

 form ; hence, the eggs were not laid 

 in strings or masses, but singly and 

 at considerable intervals. 



The flies are very hairy, especially 

 the females. The neck and even the 

 eyes are very hirsute. The eyes are 

 red, quite large and pretty, though 

 somewhat outre under the micro- 

 scope, for from between the little 

 lenses are projecting, straight, stifl' 



