37 



Mr. R. P. Williams said he had made provision for adjusting the object in 

 any vertical plane, by means of the ebonite block described in the paper ; if any 

 other alteration were required it would be necessary to soften the wax and tilt 

 the head. 



The President suggested that Mr. Ingpen meant to inquire whether, suppos- 

 ing the head were found to be embedded in such a position that the plane of 

 cutting did not coincide with the horizontal axis of the eye, it could be shifted 

 into such a plane of coincidence without the necessity of remelting the wax. 



Mr. R. P. Williams said he could not do that, but he thought it might be 

 done, and he would endeavour to do it. 



Mr. E. T. Newton asked for information upon one point which he did not 

 quite see was provided for. In cutting sections he had found it to be absolutely 

 necessary that they should be cut in fluid in order to get them off the knife. The 

 machine itself was beautifully true in all its parts, and seemed perfectly to 

 meet wants often felt, but he should like to know how he was to get the 

 section off the knife, to which it would certainly adhere after being cut ? 



Mr. R. P. Williams said he had mentioned in his paper that the knife must 

 be moistened before using with oil of turpentine, otherwise the section would 

 cling to it. When the section was cut, it would be found upon the cutter, but 

 by placing a piece of paper upon the edge, and then easing tbe section off the 

 cutter with a piece of wood cut to a thin edge, it could be easily transferred to 

 the paper, and thence to the fluid. 



Mr. Newton was doubtful whether so thin a section would bear to be pushed 

 off in this way without injury. 



Mr. R. P. Williams said of course it must not be pushed. 



The President inquired if there would be the same degree of adhesion to a 

 revolving cutter as to an ordinary shaped one ? 



Mr. R. P. Williams thought there would be about the same, but was quite 

 sure that if oil of turpentine was used, it would effectually prevent the wax 

 from adhering to the knife. He had formerly used oil for the purpose, but 

 found this softened the wax, and would, therefore, not do ; oil of turpentine did 

 not dissolve the wax, but prevented it from adhering, and enabled it to be easily 

 removed in the manner described. 



The President did not know how far the oil of turpentine would affect the 

 after process— such as staining— and asked if Mr. Williams stained his 

 sections. 



Mr. William's said he had not done so ; he did not know that it was necessary. 



The President said he had seen some very nice sections of eyes cut by Mr. 

 Mclntire, and hoped that gentleman would give them the results of his ex- 

 perience. 



Mr. Mclntire said that in cutting sections of insects' eyes he depended entirely 

 upon luck. He had seen some very beautiful sections cut by Mr. Stewart, and 

 thought he should like to try his hand at them. He accordingly got one of 

 Topping's machines, and embedded the heads in a mixture of bee's wax and oil. 

 He first tried upon the heads of flies, soaking them in spirit to harden them — 

 from six to 24 hours. Great care was required in sharpening the razor. He 

 found in practice that it was impossible to get a section of both eyes at the same 

 time. The eyes having been hardened as described, must then be put into tbe 

 wax, after which the sections could be pared away, taking care always to keep 

 the razor thoroughly moistened with spirit, and to float the sections off the 

 blade into a watch glass of spirit— they must on no account be touched 

 or they would come aoart. They should be lifted out of the spirit on a 



