SCIENCE-GOSSIP. 



271 



the tree. They cover themselves with a substance 

 like wax, which effectually protects them from 

 insecticides. If 

 this and the 

 skin be carefully 

 removed, a vast 

 number of eggs of 

 a reddish-brown 

 colour will be 

 observed lying 

 beneath. These 

 rapidly change to 

 larvae, and in a 

 few days nourish 

 themselves At 

 this stage they 

 undergo a strange 

 metamorphosis : 

 their legs drop 

 off, their eyes dis- 

 appear, and their 

 bodies exude the 

 waxy secretion 

 which ultimately 

 serves as a pro- 

 tective covering 

 Ample material 

 for study is 

 afforded English 

 microscopists on 

 the imported 

 oranges and figs 



The House Fly (ilusca domestical 



a, Adult male ; b, proboscis and palpus ot same; c, terminal joints of 

 antennae; d. head of female; c, puparium f, anterior spiracle— all 

 enlarged (original). 



There were found within the pollen-tube, near its 

 basal end, two cells, one in front of the other. 



Each of the cells 

 thus formed de- 

 velops into a 

 motile anthero- 

 zoid, two being 

 formed in each 

 pollen tube. They 

 are surrounded 

 by a spirally- 

 arranged band of 

 cilia, developed 

 from a centre - 

 some-like body 

 within the cell. 

 The mature an- 

 therozoids pass 

 into the second- 

 ary embryo-sac 

 through an ori- 

 fice in the ex- 

 tremity of the 

 pollen-tube, the 

 watery contents 

 of the pollen-tube 

 furnishing the 

 necessary water 

 for their locomo- 

 tion. These ob- 

 jects will repay 

 investigation. 



The House 

 Fly. — The num- 

 ber of eggs laid by an individual house fly, Musca 

 domistica, in one season is estimated to average 

 about J.20, and as, from 

 experiments conducted by 

 Professor Howard and 

 Mr D. W. Coquillett, it 

 shown that the total 

 life round from the de- 

 position of the egg to the 

 death of the adult is 

 approximately ten days, 

 the enormous numbers in 

 which this insect occurs 

 is plainly accounted for. 

 The experiments showed 

 that horse manure is the 

 jrite breeding place 

 of the Stuua domistica, 

 and continuous observa- 

 indicated that the 

 larvae moult twice, and 

 there are thus thre>: 

 tinct larval stages, 

 very interesting the life 

 cycle of this common 

 pest ii has been well 

 shown in a paper con- 



L. 1 1 II-. ward 



att The 



■cni stages of the 



insect are well illustrated 



in the accompanying 



■r%, and need r. 



• 



Tin Houu Ply iUutat domtitlca.) 



grown larva F Ita anterior spiracles; 



f, html ond of body showing nii.ii 

 •.I bead /. bMd from lb • 



vjn« larva from ■•' 



Bacteria of 

 Corn. — The can- 

 ning of sweet corn is an industry of remarkable 

 growth, the first corn having been packed about 

 1853, while 72,000 tons 

 were put up in the United 

 States in 1895. Recent 

 large losses (rom souring 

 have led to an investiga- 

 tion at the Massachusetts 

 Institute of Technology. 

 The souring is lound to 

 be due to fermentation 

 set up by bacteria which 

 exist on the corn in the 

 field, and are not des- 

 troyed by the temper- 

 ature of 180 to 190 , 

 at which the corn is 

 corked in the cans. To 

 effect sterilization the 

 packer places the cans 

 in retorts heated by 

 steam under pressure. 

 Experiment has shown 

 that a temperature above 

 the boiling-point of water 

 must be reached through- 

 out the corn to kill all 

 bacteria, and that ex- 

 posure of the cans for 

 sixty minutes to 250 

 I'ah. ensures complete 

 sterilization, but the min- 

 imum time and tempera- 

 ture of safety an,' .till to 

 be determined. 



A*the(oz Thi "Botanical B RATOM. — In 



» the discovery by Mr II. (, paragraph, for 



. ■ ene " 



thi! I "■' ■ 111I11 1 1 11c. liflivrnth 

 " pliocene " di.itomaccae read 



