on the Vitality andZ>ife of Germs, 243. 



aJmod at the fame time : tliof(i in the tranfparent one were 

 the lad. 



To anfwcr an oI)je6liou-<that jnight be made, that the 

 different varniflies produced a confiderable diflercnce in the^ 

 heat ill the glafl.es^ (though this diffieulty can have no rela- 

 tion tc| .thofe expofed tp the north,) I prepared, on the ^i\\ 

 of February 1798, two bent glafs tubes, one of them var- 

 nifljed black, and put hito each about a hundred of the 

 Oame eggs. Thefe I inferted in a pretty large bottle, not 

 varniflied, filled with water, which I took care frequently to 

 change, left it fliould become corrupted, and expofed them 

 to the fouth. 



On the I ft of March the4:ggs began to be hatched in the 

 black tube, and eight days after in the other; before the 

 end of the month 94 were j)atched in the black tube, while 

 in the tranfparent one there were only 41, the remainder, 

 having become gray, that i^ to fay, having p^rjfhed. 



The confiderable anticipation in the birth of the cater- 

 pillars in thefe tubes ouaht, in my opinion, to, be afcribed 

 to their being immcrfed in watp, wherp they were not 

 liable to changes of temp^^rature 'fot-violjint.,, iince the cold 

 was not greater than it had been the pre<pcding year, and 

 as the water contained in thp bpttle, during /^h^.greateft heat, 

 did not exceed 66"^ above zero ; ^vhile in the jars expofed to 

 tho.fup it rofe to -\- 88 and +'109, bqt towards the north 

 it was, only from -f 55'^ to -5-6^, a temperature fufficient to 

 hatch the eggs of thefe infedls; ^nd as the pr^fent year. this 

 degrc^e , of heat had been experienced iW9r;<^, than u Rial, it 

 appears to be very probable that ..irt ^i,s not ^^ certain period 

 of time that is necellary for hatching, but a certain degree of 

 heat. 



I repeated the fame experiments on, the pbuLena mori 

 hinti, (the^filk-worm) : the results were pcrfe6tly- analogous 

 to thdfe aboYjC mentioned. I :il|a^l not .enter^iptp., all, the. de- 

 tails, but relate tl>.ofp wj^ich I ma(|jD,ou,},^e^^s,^^^jfoj:(^p( 



Thefe eggs be^ng, pvcrcd only with "a very thin pellicle^ 

 appeared to mc very proper for the experiment j and bcfid^§ 

 this, the attention with which the- mother envelops th.em, 



II h 2 and 



