200 



HAEDWICKE'S SCIENCE-GOSSIP. 



[Nov. 1, 1869. 



MICEOSCOPY. 



Spirulina. — I beg to record a new locality for 

 Spirulina tenuissima, for which only two stations, 

 both in Wales, are given by Harvey. I found it on 

 Sept. 8th among filiform Algae, near the pier at 

 Worthing. As I only saw an isolated filament, I am 

 not quite certain of the species. If it is not 

 <S'. tenuissima, it is S. Hutchinsiee , which was un- 

 known to Harvey, and chiefly differs from the other 

 by its larger size. — D. H. Scott. 



Scale of the Eel.— May I be permitted to add 

 to the notice of the above at p. 187, that these 

 lovely scales are so often overlooked, because they 

 are situated under the outer skin, instead of upon it, 

 as in other fishes ? I have been told, but cannot 

 now recollect my authority, that it is only of late 

 years that the Jews have permitted themselves to 

 include the Eel among things to be eaten. Until 

 science, aided by the microscope, showed the falsity 

 of the notion, eels were scouted as being " without 

 scales," and consequently forbidden by the law 

 (Levit. xi. 9—12). The scales may be easily ob- 

 tained by " picking " at a piece of the skin in a 

 dried or half-dried condition with a rather stout 

 needle, when they will be jerked out. The skin 

 itself, with the contained scales mounted in balsam, 

 forms a most lovely object for the polariscope. — 

 W. W. Spicer, Havre. 



Fig. 230. Scale of Salmon (Sulmo salar). 



Salmon Scales.— In continuation of our figures 

 of the scales of freshwater fishes we give that of the 

 Salmon (Sahio salar) from specimens kindly fur- 

 nished for the purpose by Henry Lee, Esq., E.L.S. 

 Without this scale no collection would be complete, 

 as it furnishes a peculiar type not supplied by any 

 of those already given. 



Cells for Microscopic Objects. — Before your 

 readers mount many objects in the India-rubber 

 cells, described in your October number, I would 

 give them a word of caution as to my own ex- 

 perience, and that of friends here, who tried the 

 same form of celi in 1S61-C2. We found there 

 was no true adhesion between the glass and India- 

 rubber, and that a very slight jar caused the dis- 

 mounting of the whole ; next, Brunswick-black, one 

 of the most untrustworthy of cements, from its 

 tendency to flake, soon cracked and peeled off, thus 

 letting in fungoid growth ; then the cells very soon 

 perished, as the term is when the India-rubber 

 becomes brittle. We found the same objections 

 hold against gutta-percha, which has been recom- 

 mended as a cheap form of cell, with this addition, 

 that it was a wonderful nidus for fungus. Perhaps few 

 have tried more experiments in the way of cells than 

 I have ; besides those above mentioned I have, inter 

 alia, tried card-board, leather, ivory, bone, wood, lead, 

 tin, glass, brass, &c, as well as cells moulded or cut 

 from pipe-clay ; ditto with various cements, pottery, 

 electric cement, marine glue, sealing-wax, marine 

 glue and sealing-wax combined, &c. Of all I prefer, 

 among the former, glass or brass, and of the latter, 

 or home-manufactured, the glue and sealing-wax 

 combined. The brass cells, which are very cheap 

 and easy to fix, I make from brass rings ; I used to 

 employ different sized curtain-rings, until I became 

 acquainted with those of which I enclose specimens. 

 They are used by tailors as button moulds, and can 

 be purchased in three sizes, at a woollen-draper's or 

 tailor's trimming Avarehouse, at from lOd. to Is. 4d. 

 per gross ; and therefore, as regards cheapness, can 

 compete with the endless bands. Now, as to the mode 

 of fixing ; this is done by marine glue, or one of the 

 many cements used for fixing glass and brass, or re- 

 pairing glass or china. I prefer the marine glue, 

 because, when properly manipulated, it never fails, 

 and the slide will sooner break than the cell come 

 off. My modus operandi is as follows : first, centre 

 a batch of slides, and cut some marine glue into 

 pieces the size of a pin's head ; then, with wooden 

 forceps, seize one end of the slide, drop a ring on 

 centrally, place three or four pieces of glue at in- 

 tervals outside, and touching the brass ring ; hold 

 the slide over a spirit-lamp, until the glue by 

 capillary attraction runs under (care must be taken 

 not to bake too much) ; then drop the slide on wood 

 to cool, when the superfluous glue may be removed 

 with a knife. To fix the glass cover, paint the ring 

 with gold-size, and when tacky, drop on the cover ; 

 when dry, give it a coat of gold-size, and finish it off 

 with asphalte or coachmaker's varnish. If required 

 for fluid, I either paint the inside with gold-size or 

 with electroplate before fixing. If a deeper cell is 

 required, I cement two rings together. If required, 

 I will describe the sealing-wax, &c, cells, on my plan 

 of electro-plating.— T. W. Wonfor, Brighton. 



