Dr. Griffith on preserving Microscopic Objects. 113 



every reason to suppose that one day, when we are better ac- 

 quainted with the histoiy of its development, of which we are 

 entirely ignorant at present, the genus* Montagnea itself will have 

 to be placed at the head of this tribe, from which Batarrea is pro- 

 bably not so far removed as is supposed. 



XYII. — On the different modes of preseu'ving Microscopic Objects. 

 By John Wm. Griffith, M.D., F.L.S. &c. 



During the progress of microscopic experiments and examinations, 

 we are continually meeting with parts in which some peculiar struc- 

 ture is particularly well illustrated, which we are anxious to preseiwe ; 

 sometimes, for the purpose of reference and comparison, we are 

 ohliged to keep specimens of different structures by us. It is my 

 intention here to say a few words on the best methods of so doing. 



The description of these is no slight task, for it is by no means 

 easy to render a clear account of the manipulations required, so as 

 to make them applicable by others ; moreover, one in the habit of con- 

 tinually jDutting up specimens is apt to overlook mentioning certain 

 minutiae, which, from use, he is hardly aware of performing, but 

 which are essential to the perfection of the work. The main point 

 is to protect the object from injury by surrounding influences, such 

 as violence, the action of the preservative liquids, evaporation, &c. 

 This in a few cases is impossible, but in the majorit}' any alterations 

 produced in those specimens which are properly put up are so 

 slight as not to destroy their value. There are two modes of view- 

 ing microscopic objects ; one when illuminated by reflected, the other 

 by transmitted light. I shall first notice the former. 



Opake objects are of two kinds ; those preserved in the dry, 

 and those in the moist state, a. The dry ones are usually fastened 

 upon circular discs, or columns of cork, by a little gum, or solution of 

 gum mixed with isinglass ; they are then transfixed with fine pins, 

 so as to be stuck into cork, which forms the bottom of the drawer 

 in which they are arranged. Sometimes the circular flat discs of 

 cork are fastened upon glass slips, and arranged in cabinets in 

 the same manner as transparent objects. The cork must always be 

 blackened, so as to prevent the reflection of any luminous rays which 

 might interfere with the distinct vision of the object. This is ef- 

 fected in cork either by scorching or painting it over with an inti- 

 mate mixture of finely powdered lamp-black and gum-water. But 

 almost any black surfaces may be used for this purpose — black 

 velvet, silk, paper, or blackened metal. When the opake object is 



• M. Montague has very lately received valuable information on this 

 genus from M. Dunal, whicli he will no doubt sliortly publish. From the 

 observations of Dunal, it appears that all the specimens hitherto collected 

 have been imperfect. We are liappj' to hear that M. Dunal, whose letter 

 and sketches we have had the advantage of inspecting, is using every exer- 

 tion to procure this most curious and interesting production in every stage 

 of gi-owth. — Ed. 



Ann. i^' Mag. N. Hist. Fb/. xii. I 



