1882.] 



MICKOSCOPICAL JOURNAL. 



class of diatoms alive. The experi- 

 ment may be made beautifully de- 

 monstrative by the application of a 

 little soluble blue under the cover- 

 glass, with the drop containing the 

 diatoms. Whether this phenomenon 

 is the result of cilia too minute to be 

 seen, or of motion of the chlorophyll- 

 grains inside the diatoms, I could 

 never determine, though I have 

 watched for hours. Unfortunately, a 

 change in the character of my water- 

 supply has deprived me of the means 

 of continuing these investigations ; I 

 cannot now find the diatoms. I 

 would say further that I have shown 

 this object to many microscopists 

 and to the microscopical club of this 

 city. I would be glad to hear from 

 any who may have a word to say on 

 this subject 



Henry Mills. 

 Buffalo, N. Y. 



The Griffith Cell. 



BY E. H. GRIFFITH. 



The following method of making 

 cells, which I think originated with 

 myself, I have for many months used 

 with more satisfaction than any 

 other. I am pleUsed to learn that the 

 method is also very popular with mi- 

 croscopists in many States to whom 

 I have explained the process. Place 

 the slide on a turn-table, and with 

 white-zinc cement turn a circle on 

 the centre if for a transparent mount, 

 or a disc if for an opaque one, then 

 to the circle or to the disc centre a 

 common curtain ring and immediate- 

 ly paint the ring with the cement, 

 taking care not to push it from its 

 position. When dry, the cement will 

 hold the ring very firmly so that there 

 need be no fear that it will break off. 



If a shallow cell is desired the 

 rings may be flattened easily ; or, if 

 a deep one is required, several rings 

 may be securely fastened one above 

 the other by painting each one in 

 succession, in the same way that Mr. 

 Walmsley makes his excellent wax- 

 cells. If the cement does not flow 



readily add benzole ; and in case the 

 cell becomes rough, dip the brush in 

 clear benzole and smooth it. Use a 

 brush well filled with the cement to 

 secure a smooth background. With a 

 little practice a person may easily 

 make fifty beautiful and practical 

 white cells in one evening, and in a 

 few hours they will be hard and 

 ready for use. When the cover-glass 

 is to be fastened a little of the ce- 

 ment is easily applied. When dry the 

 slide may be finished with colors pre- 

 pared from tube paints mixed with 

 benzole-balsam, or with damar and 

 benzole. Before mounting, if a dark 

 background is desired, I know of 

 nothing better than a disc of as- 

 phalt of any desired size turned in 

 the centre of the ring. Over the as- 

 phalt a small sized cover-glass may 

 be used for the object to be placed 

 upon, or the asphalt may be covered 

 with shellac when dry. The object 

 may be fastened with gelatin or gum 

 arabic, or made to adhere to the 

 coat of shellac before it becomes dry. 



The New " Congress " Stand. 



This stand, made by Mr. W. H. 

 Bulloch, of Chicago, is supported by 

 a broad, flat tripod. Upon the upper 

 portion of this tripod rests a thick, 

 circular plate, from which rise two 

 stout columns that support the body 

 of the instrument. The plate rotates 

 upon the tripod, but it can be 

 clamped in any position by a screw 

 with a large milled head. The edge 

 of the plate is silvered and graduated 

 to degrees. 



The body of the instrument is sus- 

 pended at the top of the columns by 

 two trunnion joints. It can be in- 

 clined at any angle from vertical to 

 horizontal, and can be clamped by a 

 pair of screws. The limb has an un- 

 usually long and broad slide, more 

 than an inch in width by about six 

 inches in length. Near its outer edges 

 are two V-shaped grooves extending 

 the whole length of the slide. The 

 centre of the slide is cut out into a 



