66 



HARDWICKE'S SCIENCE-GOSSIP. 



[March 1, 1S67. 



MICKOSCOPY. 



Glass-cells. — I beg to enclose a rough sketch 

 'of a simple and inexpensive form of an instrument, 

 now made, but in a most complicated way, and at a 

 cost which many would not care to incur. The one 

 figured below can be made at the cost of about a 

 shilling. The advantages of this instrument are 



B 







O 



o 



Fig. 54. Glass slide drilled with three holes. 



D 





Fig. 55. Side view. Fig. 56. Upper view. 



A, cell drilled in the slide. B B, common paper screws. 



D D, thin glass covers above and below. 



great, enabling an insect (say a Daphnia or Cyclops) 

 to be kept in water in the field of an inch-and-a-half, 

 or two-inch objective, while the thin covering plates 

 enable circulation of blood, &c, to be clearly seen 

 under even these low powers. A -j^th works well also 

 with this instrument. I trust that this may be of 

 service to my fellow microscopists.— /. W. llencher. 

 P.S.— The drilled slides can be obtained of 

 Mr. Charles Baker; the screws at nearly any 

 stationer's. 



Vibbio Tbitici. — Allow me to add a supplement 

 to Mr. Fox's remarks on the Wheat Eel, contained 

 in Science-Gossip for January. The rearing 

 of these curious creatures has been a favourite 



amusement with me for a number of years, and as 

 the process is simple, and the results highly in- 

 teresting, some of your readers may perhaps be 

 disposed to put my plan in practice. I proceed 

 thus : — After selecting about eight grains of good 

 wheat, and an equal number of the infected ones, 

 I wrap them in pairs in small pieces of paper, and 

 thus plant them in my garden. Here the damp 

 earth causes the good grain to vegetate, and at the 

 same time resuscitate the eels ; and as the wheat 

 plant grows, they enter the fibrous roots, and passing 

 up the stem, enter the ear and deposit their eggs. 

 It is somewhat difficult to detect them in the stem; 

 for this purpose I take a stem long before there is 

 any appearance of the formation of the ear, and cut 

 very short sections, which I bruise in a drop of 

 water, or a glass-slide'; but the more easy and 

 pleasing part of the process is to watch them in the 

 infected grain from the first entrance till their 

 maturity. To do this, it is requisite to have the 

 wheat growing close at hand, so that daily access to 

 it can be had, and the time I recommend for com- 

 mencement is as soon as the grain begins forming 

 in the ear. The first object to be sought is the 

 parent eel filled with eggs. These, when first 

 extruded, are of a dark colour, and opaque, but 

 gradually become more transparent, at which time 

 the young eels will be seen curled up in various 

 figures, and slowly moving round in their shells, 

 from which they ultimately break forth and con- 

 tinue to live on the farinaceous matter of the grain 

 till all is consumed, when they become torpid, and 

 so remain till brought again to life by means similar 

 to those which gave activity and instinct to their 

 parents. With a low power, no difference can be 

 seen between these and the Paste Eel, except the 

 greater activity and varied sizes of the latter. But 

 the difference is very marked when carefully exa- 

 mined with a high magnifier. — A. Nicholson. 



Toubmaline. — This is a true Proteus among 

 stones : it imitates almost all the gems by the variety 

 of its colours. Thus there are brown, green, blue, 

 yellow and red Tourmalines, and of these there are 

 a great variety of tints. It is principally in Ceylon 

 that the brown and hyacinth-red Tourmalines are 

 found, sometimes mixed with those of some other 

 colour. In Spain they are chiefly brown ; and in 

 other parts of Europe a variety is found of a dark- 

 brown approaching to black. Of late years it has 

 acquired additional importance from its application 

 in the examination of objects by polarized light; 

 for if a plate of brown Tourmaline be cut parallel 

 to the axis, it absorbs one of the polarized pencils 

 of light. — Jackson's "Minerals" 



Solvent fob Caoutchouc.— I recommend the 

 best benzole as a solvent for asphaltum and india- 

 rubber, the best I found after experimentalising for 

 months. — H. B. 



