922 SEC. 18. BIOLOGY. 



3625. Parallel Compressor, with micrometric screw, specially 

 intended for the study of ova, and for observing the development 

 of lower organisms. 



Geneva Association for the Construction of Scientific In- 

 struments. 



The upper cup takes off to admit the dissecting trough. The pressure is 

 effected by means of the side adjusting screw. By moving the dissecting 

 trough with the hand a round body can be examined on all sides successively. 



The dissecting trough can hold a good quantity of water, of which no por- 

 tion comes in contact with the metal, a favourable condition for the preserva- 

 tion of live organisms. 



3626. Dr. Burdon Sanderson's hot or cold Stage, for 



use with microscope, and with arrangement for heating by gas, 

 hot water, or lamp. T. Hawks ley. 



3626a. Boiler with incubating cells. T. Hawksley. 



3627. Freezing Machine for making microscopic sections, 



by Professor Rutherford. T. Hawksley. 



3628. Saccharometer, as accessory to the large microscope, 

 from the same contributor. R. Wasserlein, Berlin. 



The saccharometer is to be regarded as an accessory to the stand of the 

 microscope. By this combination of two instruments (as the saccharometer 

 can be fitted to smaller stands) cheapness is attained. The chief aim of the 

 maker is to furnish a useful instrument, which at the same time shall be 

 specially suited to the wants of the medical chemist 'in estimating grape sugar 

 (as in diabetes). For this purpose the scale of the instrument is graduated so 

 as to indicate in whole numbers and tenths the per-centage of grape sugar. 

 For other substances a calculation is necessary. 



3629. Woolmeasurer, fitting into the Student's Micro- 

 scope. R> JVasserlein, Berlin. 



This woolmeasurer, constructed by the exhibitor, is made at the express 

 wish of Mr. Bohm, woolfactor at Leipzig. It affords the investigator the 

 possibility of a complete command over stuffs composed of vegetable or animal 

 fibres, as wool, silk, and all vegetable fabrics, so that they can be stretched and 

 extended under the microscope ; also in case the fibre is twisted, as in wool, it 

 may be evenly stretched and rotated, so that its average diameter may be 

 estimated. The apparatus allows the object which is thus stretched to be 

 placed on a glass slide, so that it can be treated with acids, c., and covered 

 with a cover glass. All this can be done without preventing the manipulation 

 described above. Threads up to a length of 1 ^ inch can be moved successively 

 across the field of the microscope. 



3630. Small Microtome, with an arrangement for the vertical 

 elevation of the objects. F. Suss, Marburg. 



3631. Larger Microtome, for the section of the spinal cord, 

 with vertical elevation and divided circle. F. Suss, Marburg. 



