On Cutting Sections of the Eyes of Insects, and on a 

 New Instrument for that purpose. 

 By R. Packenham Williams. 

 {Read Oct. 23, 1874.) 



The general subject of cutting sections of soft tissues, has been 

 so much before the Club of late, that I fear it may have lost some of 

 the interest properly belonging to so important a branch of practical 

 microscopy. Insect eye-sectioning is, however, a speciality which 

 will I am sure command a special interest ; as it is comparatively 

 speaking, a new field of labour for the enthusiastic microscopist, 

 and one in which extraordinary activity has recently been exhibited. 



Skilful dissectors have no doubt been able to make out sufficient 

 of the structure of insects' eyes to justify them in presenting the 

 ideal sections of those wondrous organs of visions, which are to 

 be met with in the various hand-books for the Microscope. 

 Indeed it must be conceded, that the ideal sections are in advance 

 of those that are real, for, are they not the results of the 

 " Scientific use of the imagination ?" and can we not conceive of 

 tilings as they ought to be, far more easily than we can execute 

 them ? I, therefore, think it unlikely that any one has ever seen, 

 or ever will see, a real section as perfect as the ideal one figured 

 on p. CG3of " Carpenter's Hand-book for the Microscope," for the 

 necessities of the case demand that a section to be as perfect 

 must be considerably thinner towards the ganglion, so as to show 

 the filamentous termination of the diaphanous bodies. 



Be that as it may, sections of wonderful perfection have been 

 exhibited from time to time in this room ; and I, as one of the 

 workers in this field, am encouraged to hope that what little 

 information I have to give, will be regarded in the light of a 

 contribution to our knowledge of a somewhat difficult subject. 



I propose treating, in the first place, of the preparation of the 

 head for cutting ; in the next place, of the method applicable, 



