HARDWICKE'S SCIENCE-GOSSIP. 



275 



but it is rather remarkable that although my friend, 

 Mr. J. S. Harrison, of this port, has placed his large 

 and valuable collection of slides (containing speci- 

 mens by all the best mounters of the day) at my 

 disposal, I never have been able to make out those 

 nerves ; and I consider it more remarkable still 

 that I have never met a microscopist who has seen 

 them. My own private impression is that writers 

 or observers sometimes draw upon their imagina- 

 tion, and describe what they would like to see, on 

 the same principle that engravers depict objects in 

 a state of perfection which cannot be attained to in 

 mounting. I believe I have somewhere in Science- 

 Gossip seen passing reference made to preparations 

 of the nervous systems of insects. If such prepara- 

 tions are practicable, then no microscopist can rest 

 satisfied until he possesses them, and I shall esteem 

 some information on this point most valuable ; as 

 also on the preparation of small entomological speci- 

 mens in such a maimer as to reveal the internal 

 structure. As an example of what I mean I may 

 say that I read an article on the brain of Pedieulus 

 capitis, written after the close observation of a 

 whole specimen stained and mounted in balsam by 

 Topping, and I at once began to strongly desire such 

 an addition to my collection. Lastly, if we would 

 attain to a truly practical knowledge of micro- 

 entomology we must have carefully-prepared sec- 

 tions of the heads, eyes, antennae, and other parts of 

 insects, and I have been satisfied by ocular demon- 

 stration that such preparations have been most suc- 

 cessfully made, chromic acid being, I believe, the 

 hardening agent. I am entirely ignorant of this 

 process, but am most desirous to have it fully 

 explained to me, and have good reason to hope that 

 many of your readers will give me the benefit of 

 their experience, should they possess sufficient 

 patience to wade through the long narration of my 

 requirements. I have, of course, in my remarks, 

 been addressing myself to micro-entomologists only. 

 — H. Lamplouffh, Hull. 



Varnish for Microscopical Cells. — Could 

 any of your correspondents give me a receipt for 

 white varnish for ringing cells ? Also, I should be 

 glad to know of any coloured varnishes suitable, — 

 rose or lake. I have tried sealing-wax varnish.— 

 IF. G. C. 



Glycerine Mounting. — In his statement as to 

 a mixture of gold-size with white lead, &c, being 

 a good cement for confining glycerine, " E. K." has 

 ignored Dr. Carpenter's advice that varnishes for 

 such purposes should never contain any solid par- 

 ticles, as sooner or later they become porous (see his 

 work on the Microscope, 5th edition, p. 236). I 

 have found amber dissolved in chloroform to be a 

 very good varnish for just keeping the glycerine 

 within bounds, as it dries almost instantly. Then 



I apply a coating of gold-size or shell-lac varnish, 

 not to extend more than possible beyond the junc- 

 tion of the cell and cover. When quite dry, wash 

 off any glycerine by a gentle stream of water, and 

 then varnish with plain gold-size, and finally with 

 some mixed with crocus of iron. — /. B. T. 



Interference of Light. — I expect J. G. R. 

 Powell will find the obscuration he complains of 

 caused by reflection from the inside of the tube of 

 his microscope. I have often been bothered myself 

 in the same way when using a deep eyepiece. I 

 don't see how to avoid it whenever a short eyepiece 

 is substituted for a longer one, so long as eyepieces 

 are of the present construction. 



The Microscopical Structure of Lycopodium 

 Sporules in relation to their Pharmaceutic 

 and Therapeutic Value.— This was the title of a 

 paper recently read before the Homoeopathic Phar- 

 maceutical Association. The author said the ap- 

 pearance of the fine dusty sporules of Lycopodium 

 in mass is well known to all pharmacists, being 

 extensively used as a harmless covering for pills, 

 also as a puff powder on account of its extreme 

 fineness ; and on the Continent not unfrequently as 

 a producer of artificial fire, from the quality it 

 possesses of flaring up when ignited. " It has often 

 struck me as a very anomalous and unexplained 

 fact that the remedial virtues of the Lycopodium 

 sporules should be ignored by the dominant school 

 of medicine, while by the smaller body of Homoeo- 

 pathic practitioners, Lycopodium has from the 

 commencement proved one of their most cherished 

 remedies. It was with a wish to solve if possible 

 this incongruity that I have recently made a series 

 of experiments with the aid of the microscope. A 

 crude examination of Lycopodium in the microscope, 

 with a one-inch objective, shows it to be composed 

 of an infinitesimal number of minute hard straw- 

 coloured particles, each about g^o^h of an inch in 

 diameter. Upon applying a quarter or one-fifth 

 objective, these little particles will be seen to possess 

 a definite regular form, each particle being a hard 

 nut, rounded ou one side, converging in triangular 

 lines, with flattened sides, to an apex on the other 

 side, and the whole surface covered with rounded 

 knobs. After pounding a small portion for a con- 

 siderable time in a Wedgewood mortar, examina- 

 tion showed the nuts not to be perceptibly altered 

 or fractured ; but on repeating the process with a 

 very minute quantity of the sporules in an agate 

 mortar and pestle, many of the nuts were found to 

 be completely fractured and their contents dispersed. 

 Conjecturing that the contents of the nut, whatever 

 its nature, contained the vital medicinal element of 

 the Lycopodium, the .broken sporules, with the 

 addition of a drop of water, were put under the 

 microscope, when a large number of unmistakable 



