Proceedings. 135 



stages of the process. An important point to be noted is 

 that the sections should be cut from material that has been 

 kept for some time in alcohol, as is usually done in botanical 

 Laboratories. If cut from fresh material the results are 

 neither so satisfactory, nor quite in agreement with those 

 described. To make the method of using the dyes as 

 intelligible as possible it may be divided into the following 

 stages : — 



1. Place the sections in the Red solution in a watch glass, 

 which should be covered to keep out the dust, and leave for at 

 least an hour. For some sections a longer time is required, and 

 none suffer from being overstained. 



2. Wash out the superfluous dye with methylated alcohol, and 

 then 



3. Place the sections in a little of the Picric and Blue 

 solution in a watch glass, covered, as before, and allow them to 

 remain in it for two or three minutes. 



4. Transfer the sections to methylated alcohol, and give them 

 two or three washes in the same, and a final one in absolute ; then 



5. Clear in oil of cloves, and mount in balsam in the usual 

 way. 



Sections that have been treated successfully in the way 



described, will be found on examination to have several of 



their tissues sharply differentiated, and to have quite a 



number of minute details strongly emphasised. In the 



first place, all the elements which have lignified walls, and 



which constitute the major part of the conducting system 



and the whole of the mechanical, have their walls of a red 



colour, more or less uniform in tint, though slight shades 



of difference are occasionally met with. Thus we can 



distinguish at a glance : — (a) the xylem elements of the 



vascular bundles, (b) the sclerenchyma of the stereom, 



and (V) any individual elements that have lost their vitality 



and become lignified. Secondly, all the elements which 



were living at the time the specimen was gathered, have 



their cell contents pricked out with blue, and stand out 



clearly separated from the dead mechanical elements and 



