( XV ) 



July 1, 1885. 

 R. M'Laculan, Esq., F.R.S., &c., President, in the chair. 



Donations to the Library were announced, and thanks voted to the 

 respective donors. 



Election of Members. 



Thomas Edmonds, Esq. (Totues, Devon), and Francis Maule Campbell, 

 Esq., F.L.S., F.Z.S., &c. (Rose Hill, Hoddesdeu), were balloted for and 

 elected Members of the Society. 



Exhibitions, dc. 

 Mr. S. Stevens exhibited specimens of a Coccus which were proving 

 very destructive to the leaves of an India-rubber plant. 



Mr. J. W. Slater read the following note : — 



The Influence of Magnetism upon Insect Development. 



" Having seen that the eggs of fowls are not normally developed if 

 subjected to magnetic currents during incubation, I thought it interesting 

 to try the effect of magnetic action upon the development of caterpillars. 

 Accordingly, having found last season six caterpillars of the common large 

 cabbage white, all evidently of the same brood, I put three of them in a box, 

 five inches in length, between the opposite poles of two bar-magnets. The 

 other three were placed in a similar box at such a distance that they could 

 not be affected by the magnets. Both lots were placed under exactly 

 identical conditions as regards light, heat, and supply of food. Two of 

 those between the magnets shrivelled up and died without passing into the 

 pupa-state. Thinking they might have been attacked by some parasite, I 

 removed them into another box and kept them for some time. As no 

 ichneumons or other parasites made their appearance, I dissected the 

 bodies carefully under tlie microscope, and found no traces of parasitic 

 injury. 



'• The remaining caterpillar, and all the three which were not exposed to 

 the magnets, became pupse in due course, and came out In May. The 

 non-magnetised lot were perfectly normal and healthy, and when released 

 after examination flew away ; but the survivor of the magnetised lot was a 

 cripple. It had merely rudimentary stumps in place of antennae, the 

 wings on the left side were expanded, and the legs on the same side were 

 smaller than those on the right side. 



" To judge from this single experiment would be obviously premature ; 

 but I hope this season to make further trials on a more extended scale." 



