1885.] 



MICROSCOPICAL JOURNAL.. 



99 



— In addition to their objectives a new 

 price-list of which was received a short 

 time ago, Messrs. H. R. Spencer & Co. 

 now offer two microscope stands, which 

 they designate as ' Nonpareil ' No. 2 and 

 No. 4, respectively, with one-inch and 

 quarter-inch objectives, for ;^42.oo and 

 $49.00. They consider the stands to be 

 ' the best low-priced stands made in the 

 United States.' 



— Mr. W. H. Curtis has favored us 

 with two neatly mounted preparations of 

 diatoms ; one a slide of five selected and 

 arranged frustules of Arachnoidiscus, the 

 other a mount of some fresh-water gather- 

 ing. The diatoms are well cleaned and 

 the mounting is well done, but highly 

 ornamental. Between two fine rings of 

 bright red color surrounding the speci- 

 mens a white ring is made in which the 

 preparer's name is written with a needle- 

 point. Outside of this, around the edge 

 of the cover-glass are dots of red and blue. 

 The ornamentation is of the same kind as 

 that on slides prepared by Mr. W. C. Wal- 

 ker. 



— Another microbe of diseases has been 

 brought to notice by the researches of 

 Boniet, who has cultivated, through six 

 generations, the microbe of mumps. It is 

 still possible (not to say probable) that 

 inoculation experiments will not fully 

 sustain the supposition that they are 

 the cause of mumps. Thus far only 

 rabbits have been subjected to such ex- 

 periments, and the results have been 

 negative. 



— Reports of the meetings of the San 

 Francisco Microscopical Society come 

 to us regularly, with much interesting 

 matter. The society seems to be in a 

 flourishing condition. At the meeting 

 of March nth, Dr. S. M. Mouser ex- 

 hibited his newly acquired microtome of 

 the Thoma pattern. It consists essenti- 

 ally of a frame of cast-iron, on which 

 slide two carriers. A large and finely- 

 finished knife is clamped to one of these, 

 which slides on a horizontal plane. The 

 second carrier (which holds the speci- 

 men to be cut) moves on an inclined 

 surface. 



Professor Thoma has based the con- 

 struction of this microtome upon the 

 principle (first theoretically deduced, and 

 then practically demonstrated) that a body 

 sliding between two inclined planes and 

 touching the latter at five points only will 

 slide evenly and exactly over such planes 



even if they be not geometrically true. 

 A knife attached to such a carrier will, 

 therefore, always cut perfectly parallel 

 sections of an object which is elevated 

 after each cut. As a practical exemplifi- 

 cation of the perfection with which the 

 above principle has been worked out in 

 the Thoma microtome, it may be stated 

 that it permits the cutting of serial sections 

 of well-hardened animal tissues of certain 

 kinds as thin as .002 mm. (.00008 in.), 

 and even such a comparatively coarse 

 tissue as liver can, if well hardened, be 

 cut to .01 mm. (.0004 in.) The ability to 

 produce sections of such wonderful deli- 

 cacy has given a great impetus to histo- 

 logical and pathological research of late. 

 Mr. Breckenfeld exhibited a Graduated 

 Blue-Glass Modifier, which has just been 

 brought out by the Bausch & Lomb 

 Optical Company. It consists of a glass 

 disk revolving upon an adapter under the 

 stage of the microscope. It is flashed 

 from clear glass to dark blue, and one- 

 half of its surface being lightly ground, 

 any desired tint of field may be obtained, 

 from white to deep blue, either trans- 

 parent or translucent, by merely revolving 

 the disk. 



— The semi-monthly meeting of the 

 San P'rancisco Microscopical Society was 

 held March 25th. Dr. C. P. Bates ex- 

 hibited an ingenious and efficient warm 

 stage, for use in the study of pure cultures 

 of bacteria and similar minute organisms. 

 A sterilized cell containing the material 

 under observation is laid upon a wooden 

 slide which rests upon the stage of the 

 microscope. This slide has a central per- 

 foration for admitting the rays necessary 

 for illumination, and is heated by two 

 twisted copper wires, which form a loop 

 directly under the culture cell, and then, 

 passing out of the slide at either end, meet 

 directly in front of it, and are there again 

 joined and prolonged a distance of sev- 

 eral inches. The free end is made to pass 

 through the perforated chimney of a small 

 lamp, and by adjusting the flame of this 

 along the wire the temperature of the cul- 

 ture cell may be raised or lowered until 

 the desired point is reached. A delicate 

 thermometer, adjustable on the slide, reg- 

 isters the temperature with great exact- 

 ness. By the peculiar arrangement of the 

 wires, the entire slide is heated with abso- 

 lute uniformity, and in this respect it is a 

 modification of, and somewhat of an im- 

 provement upon, a warm stage recently 

 described in theyb«r«rt/of the Royal Mi- 

 croscopical Society. 



