706 SUMMARY OF CURRENT RESEARCHES RELATING TO 



to the Microscope. Thus, suppose the light from the mirror to be 

 directed as in fig. 130, then if the limb is inclined to the horizontal 

 the light will still be upon the object, the incidence being, however, 

 greatly increased in obliquity. 



This result is obtained by making a sector-groove on either side of 

 the limb radial with the object on the stage. The top of the tripod 

 is provided with jaw-pieces fitting in the sector-grooves, and a clamp- 

 screw causes them to grip the limb at any position of inclination. 



The under face of the stage is flat, so as to present the least 

 obstacle to oblique illumination, and the required strength in the 

 attachment to the limb is obtained by thickening the rim on the 

 tipper edge as it approaches the limb, as devised by Mr. Tolles.* 

 Friction-stage movements carry the object. The substage fits on the 

 lower end of the limb by a dove-tail slide, which appears to be a con- 

 venient arrangement for rapidly attaching or removing it. The 

 mirror can be used as shown in fig. 130, or on the tail-piece as in 

 fig. 129. A telescope rod carries a bull's-eye lens or prism with ball- 

 and-socket joints, as shown in fig. 130. The fine adjustment is on 

 the system applied to Messrs. Swift's previous model.f 



The new Microscope is extremely steady in all positions of in- 

 clination, in this feature meriting the favourable opinion of Wale's 

 original model expressed by Dr. Carpenter.J 



Projecting Lanterns. § — Prof. C. H. Stowell describes his expe- 

 rience with a Marcy's lime-light sciopticon with one of Zentmayer's 

 microscopic attachments, using ordinary Microscope objectives (1^ 

 and 3-4ths in.), although the field is flatter and lighter if objectives 

 are used especially for this kind of work. To work nicely the gases 

 should be under heavy pressure. When the pressure in the cylinders 

 is down to 60 or 70 pounds, such good results are not obtained. 



With this simple outfit the Professor illustrates his lectures on 

 histology. A transverse section of the spinal cord of a pig can be 

 enlarged to 10 ft. in diameter on the screen. To show the nerve-cells 

 a power of 500 diameters is very easily obtained. The cells will show 

 so clearly that their poles can be counted and their nuclei clearly dis- 

 cerned. Sections of injected kidney, liver, intestine, &c., show very 

 clearly and beautifully as well. Sections of cancer will show the 

 stroma and cells. Pneumonia lung will show air-cells 6 in. in 

 diameter more or less filled with the exudate. 



One of Dr. A. Y. Moore's double-stained blood slides will show 

 the individual corpuscles and their nuclei at a distance of 20 ft. 

 from the screen very clearly, and this with a disk 6 ft. in diameter. 

 The strife and sarcolemma of muscle can be exhibited also. The 

 circulation of the blood can be exhibited, using the tongue of the frog, 

 on a disk 12 ft. in diameter. 



By a simple device opaque specimens are thrown upon the screen. 

 A frog is pithed, the thoracic walls removed, and the heart beating 



* See this Journal, i. (1881) p. 944. f Ibid., p. 297. 



J Ibid., iii. (1880) p. 1086. 



§ The Microscope, iii, (1883) pp. 51-3. 



