304 



BUMMA.RY OF CURRENT RESEARCHES RELATING TO 



both of the lamps can be used according to the degree of heat required, 

 and a thermometer can be applied if desired. 



Prof. Max ScJiultze's * (fig. 59) is figured in most foreign treatises, 

 and was the first fairly successful hot stage. 



It consists of a brass plate A, 1-2 mm. thick, notched behind so as to 

 fit to the pillar of the Microscope, and attached to the stage by clamps. It 

 has two arms B C, 170-200 mm. long and 30 mm. broad, bent forwards at 



Fig. 59. 



right angles. Spirit-lamps are placed under the ends of these arms and an 

 object on the plate (then elevated 10 mm. above the stage) can be readily 

 raised to a temperature of 35*^-45° C. A small hole at A allows light from 

 the mirror to pass to the object, the temperature of which is recorded f by 

 a thermometer F, rising obliquely above the stage, the bulb being wound 

 twice round the aperture at A. The upper part of this bulb is flat, so as 

 to lie close to the central plate, and the bulb is inclosed in a box or cover 

 to protect it from changes in the external temperature. Two wooden 

 ledges D E at each side of the box, support the apparatus on the stage 

 and retard the abstraction of heat through the stage. This apparatus 

 has a special defect according to Engelmann. The temperature of the 

 object is occasionally reduced very considerably by the metallic setting of 

 the lens and the body-tube, so that the focal distance of the objective 

 exerts a marked influence on the observations. The insertion of a bad 

 conductor of heat between the lens and the body-tube has been proposed. 

 An ivory tube 30 mm. in height applied in this manner lessens the defect 

 very materially.:}: 



Dr. Hansom in order to employ the stage for cold also, suggests making 

 it of copper instead of brass, the former metal being so much better a 



* Arch. f. Mikr. Anat., i., 1805, p. 1; Frey, H., 'Das Mikroskop,' &c. Transl. by 

 Cutter, 1880, pp. 101-2 (1 fig.); Harting, op. cit. pp. 147-8 (1 fig); Dippel, L., ' Uas 

 Mikroskop,' 2nd ed., 1882, pp. 653-5 (1 fig.); Robin, C, ' Traite du Microscope,' 1877, 

 pp. 161-2 (1 fig)- t Froy says " wirklich" and Raiivier " ai)proximativement." 



X See Frey, op. cit., pp. 101-2. 



