ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



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Lacaze-Duthiers' (fig. 114), has also a rack-and-pinion arrangement 

 and double tube but is designed to obviate the difficulties found to arise 

 in many cases from movement of the syringe, as well as unequal pressure. 

 It is attached to a heavy base, so that it will stand upright by itself, and 

 a disc is placed on the top of the piston for weights, by which the piston 

 can be made to descend automatically and at any given rate. The 



Fig. 113. 



Fig. 114. 



syringe can be placed in a vessel of warm water when it is necessary to 

 keep the injecting fluid at a given temperature. M. Eobin * preferred, 

 instead of the disc, a stretched indiarubber band, which passes through a 

 ring at the top of the piston, the ends being fastened to the cylinder. The 

 two tubes can be used for injecting two orders of vessels simultaneously. 

 Faraboeufs (fig. 115) is covered with a non-conducting material so as 



Fig. 115. 



to protect the hand from the heat when fluids are used which must be kept 

 very hot. The intervals allow the contents of the glass syringe to be seen. 



* Eobin's ' Tmit6 du Microscope,' 1877, pp. 990-1 (1 fig.). 



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