168 MEMORANDA. 



plate square to the axis of the microscope ; on sweeping 

 through the slide, if any particular form occur worthy of 

 note, its position is at once read off on the two scales, and 

 noted thus, " Triceratium favus ^% ;" the upper numbers 

 referring always to the horizontal scale, and the lower num- 

 bers to the vertical. 



If I wish at any time to find T. favus, I have merely to 

 bring the horizontal stage over 40 on its scaFe, and the vertical 

 stage over 20 on its scale, when T. favus must appear. Thus 

 the whole contents of a slide may be speedily catalogued and 

 registered, and as speedily found again when required. A 

 small arrow scratched upon each slide serves to show the 

 direction in which it is laid, for registry or reference. The 

 divisions 1 use are l-5ths of an inch ; each is again divided 

 into 10 parts : each of these may be divided by the eye into 

 half, so that when the stages do not come exactly over a divi- 

 sion, I register them thus : T. favus ^. It is obvious, that 

 when working at night these scales will be in the dark ; 1 

 then use a small silvered reflector, about two inches square, 

 which fits into a handle, and throws ample light upon either 

 of the scales, with a little management. 



In the study of diatomaceous deposits this method of 

 registering is especially serviceable, as the whole contents 

 of a cabinet may be registered in a book, and any specimen 

 referred to in a moment, without the least trouble or loss of 

 time. 



I am indebted to my esteemed friend, B. Bi'odie, Esq., for 

 the suggestion of the above contrivance. — F. Okeden, C.E. 



On the presence of Starch in the blood of an Epileptic Patient. — 



During the latter part of last year (1853) a gentleman, re- 

 siding in Toronto, troubled with epilepsy, stated to me that 

 he was desirous of having his blood examined by means of 

 the microscope, hoping thereby that something might be dis- 

 covered in it which might explain the cause of his complaint. 

 Being fully aware of the great influence which the delayed 

 excretions of the system exercise when retained in the blood, 

 I readily acceded to the request, thinking it possible that I 

 might find some changes in the blood corpuscles, or in the 

 deportment of the fluids, that might assist in the investigation 

 or serve to explain the nature of the affection. Having ob- 

 tained some blood by puncturing the finger with a lancet, 

 1 took a drop and placed it in the field of the microscope 

 — my microscope is a Nachet's, magnifying from 450 to 500 

 diameters. To the drop of blood I added some pure well- 

 water, the red corpuscles rapidly absorbed the fluid, and soon 



