870 



SUMMARY OF CUREENT RESEARCHES RELATING TO 



The tin-foil on the upper surface ends in blunt points above the 

 opening in the plate at a distance apart of about 5 mm. The object 

 is laid on these points and covered with a cover-glass. 



StrobeUs * apparatus is described by him as follows : — Cut two 

 pieces of tin-foil, 1) h, fig. 198, of about 20 mm. in breadth and 

 35 mm. in length, and place them upon the ends of a slide A so that 

 their longest side is parallel with the shortest side of the slide, the 

 ends being doubled underneath. If the tin-foil is not too thin it will 

 adhere to the slide of itself; under these can be inserted other strips 



Fig 



of tin-foil with pointed ends a a, the distance of which from each 

 other can be varied according to desire. The slide is placed upon a 

 larger glass plate B, on which two strips of tin-foil c c are cemented, 

 the latter being connected with the battery by the conducting wires 

 d d. 



The advantage claimed for this apparatus over the older forms, in 

 which the strips of tin-foil h h and a a are formed of one piece cemented 

 upon the slide, consists in the fact that (1) the space between the 

 pointed ends a a — the positive and the negative poles — can be in- 

 creased or diminished at pleasure ; (2) tin-foil with blunter or sharper 

 ends can be easily inserted ; (3) the apparatus can be fixed on the 

 same slide on which the object has been first examined, so that the 

 frequently tiresome work of transferring it is avoided ; and (4) when 

 the influence of the electricity has been observed, the further treat- 

 ment of the object and in many cases the mounting also can be done 

 upon the same slide, after the tin-foil has been removed. 



Strieker describes f his apparatus as follows : — " It is not prac- 

 ticable to carry out tlae examination of tissues under the influence 

 of electrical currents with the same elegance of detail as can be 

 accomplished when a simple slide only is employed. The single 

 circumstance that the tin-foil in adhering to the glass makes the 

 surface irregular and uneven renders it necessary that the sections 

 of the preparation should be thicker, and proportionately interferes 

 with the investigation by means of high powers. I endeavour 

 "therefore to combine my researches with electrical currents with 

 those conducted in the gas-cell (made by forming a ring of putty 

 on a slide with two tubes passing through it). Bj this means I am 



» Zeitschr. f. Instrumentenk., ii. (1882) pp. 274-5 (1 fig.). 

 660 (1 fi-.). 

 f Op. cit., p. xxiii. 



Dippel, op. cit.. 



