262 Annals Entomological Society of America [Vol. VI^ 



9 — 3, 3, 3, 3, from Bussey Institution, July, gave 



1 9 —3, a /be, 3, 3. 

 9 — 3, 3, 3, 3, from Bussey, July, gave:* 



30 cf(^— 3, 3, 3, 3. 34 9 9—3,3,3,3. 



1 d —3, ac, 3, 3. 



2 9 9 — 3, 3, 3, 3, taken at Bussey Institution, gave: 



191 0^0^-3, 3, 3, 3. 203 9 9—3, 3, 3, 3. 



2 d^ cf — 3, ac, 3, 3. 3 rf'c?'— 3, 2, 3, 3. 



2 cf d'— 3, 3, 2, 3. \& — 3, ab, 3, 3. 



1 cf —3, 3, ac, 3. 1 9 —3, 2, 2, 3. 



1 & —3, ac, 2, 3. 

 1 9 — 3, 3, 3, 3, from Bussey Institution, Nov. 20, gave: 



124 cf 0^—3, 3, 3, 3. 118 9 9—3,3,3,3. 



1 9 —3, 3, 2, 3. 1 o^— 3, 2, 3, 3. 



1 d —3, ac, 3, 3. 



1 9 — 3, 3, 3, 3, from Bussey Institution, Nov. 18, gave: 



25 c^ d^— 3. 3, 3, 3. 34 9 9—3,3,3,3. 



2 9 9—3, 3, ac, 3. 1 9—3, ac, 3, 3. 



19 — 3, a / be, 3, 3. I & —a .' be, 3, 3, 3. 



1 9 — 3, 3, 3, 3, from scow, Boston, Aug. 8, gave: 



17 c? 0^—3, 3, 3, 3. 19 9 9—3,3,3,3. 



1 9 —3, 3, a / be, 3. 



Thus the progeny of normal 9 9 (3, 3, 3, 3.) show consider- 

 able variation, and it is readily observed that this variation 

 tends in some cases to reduction of bristles, in other cases to- 

 addition of bristles, while both tendencies may be observed in 

 the same family. Taking the totals of these families we have 

 normal cf cf 589, normal 9 9 410, variants by addition, 12 cf cT 

 and 16 9 9; and variants by reduction, 21 cf cf' and 699. 

 This gives 2.6% variants by addition and 2.5% variants by 

 reduction. 



Let us now consider the families of L. sericata produced by 

 mothers abnormal by reduction. 



d and 9' — 3, 3, 2, 3, taken at scow, Boston, Oct. 17, put in same box, gave: 

 13 d^ c?— 3, 3, 3, 3. 8 9 9—3,3,3.3. 



1 d —3, 3, 2, 3. 1 d^ —3, ac, 3, 3: 



1 d —3, ac, ac, 3. 1 d —3, 3, 2, 3. 



2 9 9—3, 2, 3, 3, 



9—3, 2, 3, 3, taken at scow, Boston, Aug. 8, gave: 



32 d' d'— 3, 3, 3, 3. 22 9 9—3,3,3,3. 



1 d —3, ac, 3, 3. la" —3, 3, ac, 3. 



1 d —3, 3, ab, 3. 1 d —3, 2, 3, 3. 



1 d —3, ac, 2, 3. 



*By reason of an imperfection in the technique at this point, this culture may 

 have been contaminated from flies outside. The results are therefore, not 

 averaged in with the total. 



