416 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and Grain's stain destroyed all vegetative forms of bacteria by virtue of 

 the independent bactericidal action of anilin and iodin respectively. 



Demonstrating the Structure of Mixed Nerves.* — S. W. Ranson 

 used the human vagus nerve, and made sections some distance below 

 the nodose ganglion. The steps of the technique were as follows : — 

 The animal is exsanguinated and the desired tissue promptly removed 

 and placed in absolute alcohol containing 1 p.c. strong ammonia for 

 forty-eight hours, rinsed in distilled water, put in pyridin for thirty- 

 four hours, washed thoroughly in distilled water for twenty-four hours, 

 placed in 2 p.c. silver nitrate at 35° C. in the dark for three days, rinsed 

 in water and placed for one day in a 4 p.c. solution of pyrogallic acid in 

 5 p.c. formalin. Paraffin sections are made. Medullated axons are 

 stained yellow and are surrounded by a colourless ring of myelin. Non- 

 medullated fibres are stained black, and are sharply differentiated from 

 the light yellow endoneurium. 



(5) Mounting - , including: Slides, Preservative Fluids, etc. 



Method of Marking a given Object for Future Reference on a 

 Mounted Slide.f — First find the object, says J. Burton, then with a 

 fine camel-hair or sable brush carefully place a dot of water-colour over 

 it large enough to be seen with the naked eye, set it on one side to dry. 

 When dry put the slide on the turntable with the dot accurately in the 

 centre and turn a ring round it with any dark cement you may have in 

 use ; when this is hard the water-colour can be removed with a damp 

 brush and the cover can be carefully cleaned with a piece of soft rag. 



"When the object is very small a more complicated variety of the 

 foregoing plan is adopted. Again, first find the object with a suitable 

 power such as ^ in. or ■£- in., and let the specimen be as accurately 

 placed in the centre of the field as possible ; then substitute for this 

 power, preferably a water-immersion objective, say y 1 ^, put on the 

 front lens a small drop of water, and carefully focus. It is necessary 

 that the slide should not be moved after contact is made, as it is desir- 

 able to keep the drop of water as small as possible. When the object is 

 recognized as in the centre of the field, raise the Microscope tube rather 

 sharply and a small circular spot of water will be left on the cover-glass 

 right over the desired place. Now stain this spot with water-colour as 

 in the other case — I always use the carmine kept for feeding infusoria, 

 etc., but any colour will do. When this is dry the slide may be roughly 

 examined and the object will be seen through the coat of colour, which 

 for this purpose should not be too thick. If it be rightly placed, proceed 

 as before, puting a fine ring of suitable size round the spot with some 

 dark cement, and when this is dry carefully clean off the colour, and the 

 arrangement is complete. Water-immersion lenses are not very com- 

 monly used now, and if the microscopist does not happen to possess one 



* Anat. Anzeig., xlvi. (1914) pp. 522-5 (1 fig.). 



t Journ. Quekett. Micr. Club, xii. (1914) pp. 311-12. 



