266 SUMMARY OF CURRENT RESEARCHES RELATING TO 



years perhaps, the publication of our work, all the drawings of which 

 have been made or perfected by homogeneous-immersion objectives." 



Vertical Illuminator for examining Histological Elements.* — 

 Dr. E. van Ermengem commends the vertical illuminator for the 

 illumination of such of the histological elements as can be mounted 

 on the cover-glass dry. " Blood-corpuscles present an extraordinary 

 appearance, their colour a lively red, their relief very appreciable, 

 and the slightest inequalities on their surface clearly visible." Good 

 results had also been obtained in the examination of semen, mucus, 

 pus, and liquids containing bacteria, &c. ; also of the minute structure 

 of muscles and nerve-fibres. 



Griffith's Parabolic Reflector.f^Mr. W. H. Tivy describes a 

 method suggested to him by Mr. E. H. Griffith for utilizing a spoon 

 for a " parabolic " reflector. Wind a clean copper wire of ,5^^ inch 

 diameter closely round the base of an objective three times, twisting 

 and bending the ends for a length sufficient to reach a little beyond 

 the end of the objective. Cut a section of about half an inch from the 

 bowl of a new plated teaspoon, and solder the convex side to the ends 

 of the wire, also making the loop solid with solder, and filing it up 

 to a good fit and figure, so that it will slip easily on and off the 

 objective. The reflector is adjusted by bending the wire. " Thus I 

 have a handy and useful piece of apparatus, at the cost of the spoon, 

 30 cents." 



Forrest's Compressorium. — This compressorium (Fig. 50), de- 

 signed by Mr. H. E. Forrest, is specially constructed with a view 

 to cheapness. It consists of a strong glass (or if desii-ed brass) plate, 



Fig. 50. 



3 inches by IJ inches, with ground edges. A small brass screw 

 passes through the plate, the point projecting upwards through it 

 about J inch. A brass arm, bent so as to form a spring, rotates upon 

 the screw as on a pivot, and carries at one end a brass ring holding a 

 thin cover-glass, 1 inch in diameter, which covers the centre of the 

 plate when in use. A milled nut works upon the screw above the 

 arm, and when screwed down brings the cover-glass in contact with 

 the glass plate. The spring acts upon and raises the cover, if the 

 nut is unscrewed, so that the two glasses can be fixed at any degree 

 of proximity required, 



Julien's Stage Heating Apparatus.^ — In a paper on the examina- 

 tion of carbon dioxide in the fluid cavities of topaz, Mr. A. A. Julien 

 thus describes the method employed in his investigations. 



* Bull. Soc. Belg. Micr., vii. (1881) pp. xxxvii.-xl. 



t Amer. Mon. Micr. Joiirn., ii. (1881) p. 238. 



X Jourii. Amer. Chem. Soc, iii. (1881) 12 pp. and 4 figs. 



