HARDWICKE'S SCIENCE-GOSSIP. 



217 



GRAPHIC MICROSCOPY. 



By E. T. D. 



No. X. — Eggs of House-Fly. 



N form, colour, opal- 

 escence, and as 

 exhibiting elegant- 

 sculptured mark- 

 ings, the eggs of 

 insects afford a 

 class of micro- 

 scopic objects of 

 engaging interest. 

 Numerous as 

 they must be, they 

 are rather difficult 

 to find and iden- 

 tify ; a knowledge 

 of the habits of the 

 insect and its food- 

 supply are the best 

 clues, but even 

 then they often 

 evade detection. 

 The common house-fly (^Musca doi?icst'ica), ubiqui- 

 tous, residentiary, and numerous as it may seem in 

 the dwelling-house, even invading the sacred 

 drawing-room, is found in far greater numbers in 

 gardens and the surroundings of domestic ofHces ; 

 and it is only in obscure and neglected places where 

 their elegantly-winged eggs are discovered, under 

 circumstances depending on the economy of the 

 creature, where the larvce, when hatched, find 

 sustenance, generally in moist putrefying substances ; 

 under such conditions, 60 to So eggs are deposited, in 

 groups of a few ; the laying is repeated after 

 intervals, the eggs hatch in two or three days, and 

 the perfect insect so quickly arrives at maturity that 

 it has been calculated and placed on authoritative 

 record, a single female in one season, through four 

 generations, may produce two million descendants. 

 To check this enorrrious fecundity, eggs are often 

 placed in unfavourable places, when hatched, food 

 failing, the larvse again become the prey of enemies ; 

 the eggs may be sought for in neglected places, rarely 

 inside an orderly dwelling. The fly only enters into 

 the domesticity of the house when in perfect condition 

 No. 238. — October 1884. 



of trimness and cleanliness ; occasionally its instincts 

 may lead it into a pantry, lured by the odour of its 

 attractions ; the eggs may be cultivated under 

 favourable circumstances, but the conditions should 

 be watched, as they hatch quickly. 



The general anatomy of the insect is not touched 

 upon ; past volumes of this journal are replete with 

 accurate information, and the subject is ably 

 exhausted in Mr. Samuelson's book, " The Earthworm 

 and the House-fly." 



Serious accusations have been made against the 

 house-fly. A writer in the " Times " of the 8th of 

 August last suggested that "savants," to detect 

 infective germs, ought to " examine the feet of flies," 

 as by such contacts, microbes or bacilli might be 

 disseminated, and, if proved, we could "protect our- 

 selves from disease by excluding flies from everything 

 we eat or drink." This provisional elimination of the 

 diptera (and to be effective it would include the whole 

 group) from the equilibrium of existences is a bold 

 idea, even in these days of bacillimania, and would 

 establish a condition of things of startling interest. 



Consider the one friendly fly, which we aU 

 know and have seen in the quietude of evening 

 marching over the book, paper, or drawing, under the 

 full glare of the lamp : revisiting at the same time, 

 under the same conditions, evening after evening 

 — a singular instance of sociability. He parades 

 and jerks along in a somewhat weak j| and inane 

 manner (the season being over), and with a familiarity 

 bordering upon insolence, settling down within an 

 inch of your pen or pencil to dust himself with 

 scrupulous care, sweeping his legs over his head, and 

 skimming his M'ings, finally washing with " imper- 

 ceptible soap, in invisible water," and shuffling the 

 result on to the paper. Shall he be accused of thus 

 depositing the germs of disease 1 



Flies, generally, are unpopular ; every one dislikes 

 them ; inventions have been devised to " keep them 

 down ; " they have been severely censured in the 

 writings of the early ecclesiastics, who have accused 

 them of "immorality," as "enemies to sleep," 

 "satellites of man," "importunate dependents of 



