M. C. COOKE ON BLACK MOULDS. 267 



important element is obtained, at least to a scientific man, who 

 finds that life is all too short, a great economy of time. 



The method which I have pursued for permanent mounting has 

 been a rough and ready one, just sufficient to obtain the objects in 

 view, and nothing more. I remove a small fragment of the mould, 

 or other object, on the point of a dissecting knife, place it in the 

 centre of a slip of glass, add a small drop of spirits of wine just 

 enough to saturate the mould, separate the threads with a needle, if 

 necessary, and then, as all the superfluous spirit will have evaporated, 

 drop a small drop of pure glycerine on the object. A square glass 

 cover (I always use 5-eighths) is placed on the object, and pressed 

 down. If a proper sized drop of glycerine has been estimated, this 

 will just spread out to the edge of the cover ; if too much, it will 

 flow out at the edges, and may be wiped away with a camel hair 

 pencil ; if too little, then more can be insinuated at the edges until 

 the whole is filled. A brass clip then holds the object in its place. 

 The edges of the thin glass must next be cemented to the slide. 

 This I accomplish by the use of gum dammar dissolved in benzole, 

 luting the edges with a small brush. The clip is kept in its place 

 for 24 hours or more, until the dammar is sufficiently dry to permit 

 of its removal, but before the slide is laid down it is indispensable 

 that a label should be attached, with the name of the object, the 

 source whence obtained, and all other information necessary to 

 secure its ultimate utility and authenticity to its fullest extent. 



As to the glycerine and the dammar, are these the best substances 

 for the purpose ? From present experience I should say that they 

 are. With glycerine I have found no shrinking and no alteration in 

 size or colour of the sporidia over a period of several years ; I have 

 suffered no inconvenience from the growth of parasitic moulds upon 

 the preparation ; I have noticed no instances of the spores themselves 

 commencing to germinate after having been mounted, and if the 

 mounting has been properly performed, and ordinary care observed 

 to keep the slides flat, and prevent unfair usage, no leakage, or at 

 most not more than one per cent, which might be attributed probably 

 to some slight imperfection in the mounting. 



The advantages possessed also by the gum dammar dissolved in 

 benzole, are now so widely and generally estimated, that it is scarcely 

 necessary to enumerate them. It may be observed, however, that 

 in using it as a cement where glycerine is employed, there is a very 

 great advantage in the readiness with which the dammar adheres to 



