HARDWICKE'S S CIE NCE -GOSSIP. 



183 



and oil of cloves to the mounting medium. In 

 the oil of cloves he found they would coil up if they 

 were not prevented by a heavy cover-glass being 

 laid upon them. 



Origin of Blood-corpuscles.— Dr. II. D. 

 Schmidt, of New Orleans, has recently published 

 his observations on this subject. His investigations 

 were directed chiefly to human embryos six weeks 

 old and upwards. lie states that the nucleus only 

 of the colourless blood-corpuscles is developed into 

 the red corpuscle, imd confirms the prevalent 

 opinion that the spleen and lymphatic glands are 

 the permanent blood-formative organs. Dr. Schmidt 

 regards the blood-corpuscle as a gland-cell destined 

 to promote within itself the transformation, into 

 other elements, of certain materials derived from 

 the liquor sanguinis, and, when matured, as giving 

 back directly to the "liquor sanguinis," by its 

 final dissolution, its secretion, consisting of its own 

 body. 



Raphides. — I like to see these best in their 

 natural position in the plant. Some will show by 

 merely putting the skiu between two glasses with 

 balsam or watei", or by peeling a piece of the cuticle 

 off. The thin-coloured skin of the bulb of tlie 

 hyacinth shows them very nicely, and so does the 

 skin of the garlic. — S. T. Scott. 



PoLARiscoPE Objects.— I don't know whether 

 the objects are known, but I find that the hairs of 

 Lithospernmm officinale make beautiful polariscope 

 settings. Those from the stem are best, and are 

 easily detached by scraping. They are insoluble in 

 pure nitric acid. In appearance they rather re- 

 semble the hairs of the stinging-nettle, appear 

 lioUow, and there is a bulb at the base, but the 

 pldut can be freely handled ; so probably possesses 

 no urticating properties. — W. H. 



Straw Paper as a Polarizing Object.— A 

 surgeon of some repute attending me during a short 

 illness, seeing the microscope upon my table in one 

 of his visits, made the remark of " How little prac- 

 tical use the instrument was in connection with the 

 household." Coming from such a man, the observa- 

 tion set me thinking, and, feeling a little chagrined 

 that any slight should be offered to my pet stud}', I 

 afterwards made it a point of examining all objects 

 of a common and suitable nature that happened to 

 fall in my way, and i have found tlie microscope of 

 much use in detecting many adulterations both in 

 food and materials for clothing, though I fear I 

 have not aliogelher made a " clear case " against 

 my medical friend's remark. At the risk, however, 

 of placing myself in the somewhat unenviable posi- 

 tion of the grocer and his lump of sugar, 1 am 

 induced to send you a slide of straw-paper that 

 accidentally fell in my way, and which, from its 

 appearance, seemed principally composed of straw 



' fibre. On looking at it through a small lens, the 

 thought occurred to me whether the structure and 

 cuticle of the straw had been entirely obliterated in 

 reducing it to the pulp for paper. On more minute 

 examination with a half-inch objective, I found the 

 straw had not been entirely broken up, while the 

 cuticle was not difficult to be traced in many places. 

 I need scarcely add that unless the straw can be 

 thoroughly reduced to pulp, the material can only 

 be used in the commonest or coarsest of paper. I 

 afterwards tried the paper as a polarizing object, 

 using blue and yello^v selenite, and was so pleased 

 with it that I am inclined to believe that had it 

 fgrmed one of the objects shown at the Quekett 

 soiree it would have been found not the least in- 

 teresting and attractive among some of the (perhaps 

 ■very common) Q\)]Qcis.— Hugh Gilbert. 



Dammar Yarnish. — In the January part of 

 Science-Gossip (p. IS), your correspondent "P.K." 

 says : — "My experience of soft cements is that in a 

 shorter or longer period they almost invariably 

 run in, and I much fear gum dammar will not 

 prove an exception." Seeing this the other even- 

 ing, on looking over the back numbers, I was 

 induced to send, for the information of " F. K." and 

 such of your readers whom it may interest, au 

 account of the preparation of the gum-dammar 

 varnish as used very extensively by Dr. Klein and 

 other well-known histologists at the Brown Institu- 

 tion. The description of it is condensed from 

 Sanderson's " Physiological Laboratory," the histo- 

 logical part of which is written by Dr. Klein :— 

 Gum dammar^ 1 oz. ; turpentine, 2 oz. ; dissolve. 

 Gum mastic, i oz. ; chloroform, 2 oz. ; dissolve. 

 The two solutions are to be separately filtered, and 

 then mixed. As for its utility, the fact that it is the 

 varnish in use at the Brown Institution, says more 

 in its favour than I could if I wrote a foolscap sheet 

 on the subject. But, speaking from expeiience, I 

 must say it is far better than any I have ever used. 

 —F. a S. 



Mounting Objects in Cells containing 

 Fluid. — Prof. Busk describes, in the last number 

 of the Quarterli/ Journal of 3Iicroscopical Science, 

 his method of using cement for the above purpose. 

 The advantage it possesses arises chiefly from the 

 circumstance that it can be used under water or 

 weak spirit, so that the cover can be affixed beneath 

 the surface of the fluid, and thus the admission of 

 air-bubbles can be effectually prevented. It has 

 also the advantage of retaining its adhesive pro- 

 perty for several days if requisite. The preparation 

 (which may be termed " caoutchouc size ") is pre- 

 pared by melting pieces of caoutchouc in an iron or 

 porcelain cup until it is reduced to the condition of 

 a very viscid tar. As this tar, however, in its primi- 

 tive state, is too viscid for use, it should be 

 dissolved in benzine, so as to form a fluid of 



