1891.] MICKOSCOPICAL JOURNAL. 253 



ment one of the requisites for a well-kept store, and use it as often as 

 possible. Local societies assist in this direction. While the micro- 

 scope is a necessary instrument for the use of the educated pharmacist, 

 it is also serviceable for amusement. The pestle and mortar should 

 not leave the laboratory, but the microscope will grace the home and 

 entertain a drawing-room of visitors. Teachers can point this out dur- 

 ing the course of instructions, and occasionally use specimens suitable 

 for such occasions as social gatherings. 



The course of instructions must not be closed without reference to 

 the literature of microscopy. Each teacher will have individual ideas 

 as to books and periodicals, but all must agree that it is desirable to 

 keep posted on current topics, and each owner of a microscope should 

 take one or more periodicals. 



o 



A Costly Microscope. — Among the exhibits at the World's Fair 

 will be a microscope made by a Munich firm at a cost of $8,750. 

 ElecLilcity furnishes and regulates the source of light, which, placed in 

 the focus of a parabolic aluminum reflector, reaches an intensity of 

 11,000 candle power. There is an automatic mechanism, worked by 

 electricity, for the centering of the quadruple condensers and illuminat- 

 ing the lenses, and there is also an arrangement for the exact control of 

 the distance of the carbon point. The instrument is provided with an 

 elaborate cooling machine, which is rendered necessary by the extreme 

 heat generated by the illuminating arrangement. The magnifying 

 power of the apparatus with ordinary objectives is about 1 1 ,000 diame- 

 ters, but with the oil immersion this can be increased to 16,000. — Brit- 

 ish Med. Jour. 



o 



Photographing in Colors. — The method by which Mr. Frederick 

 E. Ives, of Philadelphia, has solved the problem of photography in 

 colors is something as follows : Three negatives are made from the 

 same point of view on ordinary orthochromatic dry plates, one by- 

 means of die red light rays, one by the blue, and one by the green. 

 From these negatives positives are made, which are projected upon a 

 screen, the three images being superimposed. The light passing through 

 each of these positives is colored by suitably tinted glasses, correspond- 

 ing to the light rays used in securing the negatives. The resulting image 

 on the screen appears in the colors of the original. 



o 



Luminosity of Plants. — In Science Gossip for September, 1S91, 

 Canon Russell records the obsei-vation of phosphorescence in the flowers 

 and leaves of the marigold, the nasturtium, and the geranium. The 

 phenomenon is observable in the dark by the naked eye, but becomes 

 much more evident when a leaf is placed under the microscope, when 

 the leaf can be seen by its own light. 



o 



Sea-Nettles. — During the autumn the salt water teems with irritat- 

 ing swarms of j\fcdusidcc. Sometimes the stinging filaments con- 

 tained in the thread-cells of these animals prove very unpleasant to 

 bathers. Recently a bather who came in cpntact with sea-jelly was 

 obliged to send for medical assistance to obtain relief from the smarting 

 produced. As a rule, those Medusa which are uniformly bluish- 

 white in color are iyert, while those of smaller size and with reddish- 

 brown tentacula possess well-marked irritant properties. — Lancet. 



