Oct. 1, 1865.] 



SCIENCE-GOSSIP. 



237 



MICROSCOPY. 



Photo-microgeapks.— In a recent number of the 

 British Journal of Photography, Mr. John Bockett 

 tas recently detailed his method for the production 

 of Photo-micrographs by means of an ordinary laud- 

 scape lens and camera. With regard to the expo- 

 sure requisite, he says:— "The exuvia of spider, 

 skin of caterpillar, leg of beetle, and the star-fish, 

 were all done in open daylight, through an eighth, of 

 an inch stop, in one minute and a quarter." 



Microscopic Lamp. — A good microscopic lamp 

 is stated by Dr. Beale to still be a desideratum, and 

 as with high powers, and also binocular microscopes, 

 the importance of having a superabundance of light 

 is imperative, I beg to submit to your readers a 

 description of a lamp which I have had made (and 

 which will be exhibited at the Nortli -Eastern Exhibi- 

 tion at the Agricultural Hall, Islington), answering 

 every purpose. It has been in use quite three years. 

 Its construction is as follows : — A brass circular 

 foot is countersunk into a broad base of mahogany 

 (thereby obtaining stability without adding much to 

 its w^eight), carrying a main stem. Upon this glides 

 another tube (to the bottom of which is fitted a 

 clamping screw), as also a spring holder to carry a 

 Belm.ontine lamp. Sliding upon this tube are two 

 pieces of apparatus, one a reflector and the other a 

 condenser ; the latter about 2 inches in diameter, 

 the former from 3^ to 4 inches, and of the same or 

 little longer focus than the distance which inter- 

 venes between it and the convex side of the plano- 

 convex lens of the condenser. A shade covers the 

 reflecting and refracting apparatus. With regard 

 to its arrangement when in use, it is only necessary 

 after the lamp is lit to move the reflector by slipping 

 it up and down on the auxiliary tube, until the 

 bull's-eye condenser is equably illuminated, which 

 can easily be seen by placing a small disc of white 

 card upon the plane surface of the condenser. If 

 the whole has been arranged for transparent objects 

 as above, and it is required to be used to show 

 opaque objects, the auxiliary tube has only to be 

 raised, and the arrangement previously alluded to 

 still remains intact, the said alteration not being at- 

 tended with the least trouble. It burns Belmontine, 

 which I find far preferable to parafine, being with- 

 out any smell, and, as I think, with all due deference 

 to Mr. Hall's late deductions, equal to it in light. 

 By its aid I can in my binocular use a i-inch bull's- 

 eye piece most advantageously. The light with the 

 lower powers is so intense that a ground or neutral 

 tint glass slide must be used.— /o/^;i Bockett. 



ClECtTLATING CABINET OF OBJECTS.— About sis 



months ago some microscopists in Oldham and its 

 neighbourhood formed a circulating cabinet of 

 objects. Not knowing that there is anything of the 

 sort in othe: towns, I will cndeavoui' to describe it. 



In the first place we have as many tnys as there 

 are members, upon which each member puts six 

 objects, in a horizontal position, held down by 

 an elastic band. To prevent one tray from touching 

 the objects on another, a bead runs all round each, 

 about a quarter of an inch deep : the whole are en- 

 closed in a box made for the purpose. Each member 

 changes the objects on his own tray every time the 

 cabinet comes round to him, and he retains it one 

 week to examine the objects on the other trays. A 

 small memorandum-book, in which are written a few 

 short rules, the remaining space being left for re- 

 marks and suggestions, together with a stamp-case, 

 to receive the contributions of the members, which 

 goes along with the cabinet. The expenses of 

 carriage, &c., are taken out of this stamp-case. We 

 find this arrangement to work very well, and have 

 not had an object broken yet. — Johi Butterworth. 



PoLLEK. — Your correspondent " E. G. M." directs 

 the attention of your readers to the pollen of the 

 (Enothera, or Evening Primrose. I have seen the 

 pollen of Oenothera offered for sale by dealers iu 

 microscopic objects, and have mounted several slides 

 of it for my own use and for exchange with friends. 

 1 think the most beautiful pollen-grains are those 

 of the common Marsh Mallow, or of the Garden 

 Mallow, either of which may be had iu great abund- 

 ance. They are superior to the Passion-flower, 

 Hollyhock, Dahlia, or Evening Primrose. Indeed, 

 I know of no pollen worthy of comparison with 

 them. — T. P. Barkas. 



Cilia on Diatomace^.— A few days ago, while 

 examining a recent gathering of fresh-water Diatoma- 

 ce(B, I had my attention arrested by peculiar motions 

 near a frustule of Nitzschia sigmoidea. The frustule 

 itself was perfectly stationary, but it was surrounded 

 by a considerable quantity of gritty matter, which 

 was in motion. I observed closely, to see if any 

 animalcules or small diatoms were present, and 

 could not recognize any within the field of the micro- 

 scope. The matter surrounding the Nitzschia was 

 broken up into small patches and fragments, and 

 the phenomenon that presented itself w^as the rapid 

 motion of single and accumulated particles of foreign 

 matter down the sides of the Nitzschia, which was 

 lying perpendicularly to the line of vision. The 

 motions were along the sides of the diatom, and all 

 downwards. That direction of motion could not be 

 caused by mere gravitation of the particles, because, 

 as an erector was not used, the apparently downward 

 motion would be in reality upward, and upward 

 motion, under the circumstances, and to such an 

 extent, could only, as it appears to me, be accom- 

 plished by the action of cilia flashing in one direc- 

 tion. Endosmose and Exosm.ose, or any other pro- 

 posed theory to account for the movements of 

 Diatomacece, w"ill not explain the motions of the 

 ree particles as above described— .2'. B. Barkas, 



