ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



651 



warm water to freely get round the abdominal contents : the mass 

 thus gets into every organ and into every part of an organ evenly. 



We now connect the pressure bottle with the manometer and with 

 the Higginson's syringe, as shown in fig. 117, also with the mass 

 bottle. The tube of the mass bottle, which is to convey the mass 

 away from the bottle, is now clamped, as shown at C, fig. 118, and 

 must never for an instant be allowed to get out of the warm water 

 into the cold air. 



Fig. 118. 



Having our small basin full of water, we now squeeze the Higgin- 

 son's syringe, watching the manometer, to raise the mercury half an 

 inch. This done, we remove the clamp from the efflux tube, and the 

 red fluid after driving out a few air-bubbles begins to flow out ; we 

 at once make the connection, and all quicksands are passed if we have 

 tied in our nozzles properly into the artery and the connecting part, 

 and fastened in our stoppers thoroughly into our Woulff's bottles. 



Our task is easy now : all we do is to seize the head of the animal, 

 which should be to our left, with our left hand, to watch the pale 

 gums, tongue, and eyelids become suffused with a pale blush which 

 gradually deepens, whilst we gently squeeze and relax the barrel of 

 the syringe and glance at the mercury from time to time. When the 

 mercury has risen four, or at most five inches, the whole animal will 

 be completely injected: the visible mucous membranes and bowels 

 will be dark-red and much swollen. 



We now remove the animal, and place it in ice-cold water under 

 a common water-tap for an hour or two, and divide it into parts as 

 required. This method of applying pressure is wonderfully delicate ; 

 thus, whilst we can raise the mercury in the manometer almost imper- 

 ceptibly, one entire compression of the barrel raises the mercury 

 one inch." 



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