18S9] MICitOSCOt>ICAL JOURNAL. 2l5 



microtome so that it will encounter the knife cornerwiae, 

 and the cutter must be used with a combined forward 

 and transverse movement. If it is desired to mount the 

 sections serially, they must he laid with a spatula on a 

 glass slip kept wetted with alcohol in rotation as cut, and 

 touching each other, which brings us at once to the 

 making of serial sections. 



Serial Sections. — Celloidin is particularly suitable for 

 this department of microscopical work, and the method is 

 surprisingly simple and effective. Transfer the sections 

 as cut to a shallow, tiat porcelain tray, the bottom of 

 which is just covered with Yozof alcohol, or they may be 

 laid on blotting-paper similarly wetted. Take every care 

 that they do not float about and mix, and when some forty 

 to fifty have been cut, arrange in a long ribbon on a 3 by 

 1 slip wetted with alcohol, and almost the full length of 

 the slip. Let the squares of celloidin just touch each 

 other, lifting into position with a fine copper or alumin- 

 ium spatula. With a glass dipper allow a drop or two of 

 absolute alcohol, to which has been added the slightest 

 trace of water to trickle over the sections ; and after 

 draining it off, with a second dipper drop a little very 

 thin collodion or celloidin solution over them, spreading 

 it thinly with the glass rod. This is quite simple, and 

 the sections are not easily displaced. 



When the entire ribbon has been thus covered, and the 

 solution has been skinned, transfer the whole to the 70 

 per cent alcohol bath, when in a minute or two the long 

 ribbon can be lifted with a scalpel, trimmed, and peeled 

 off. Proceed in the same way wi.th the others until a 

 consecutive series of ribbons is obtained. These may be 

 cut in two, and arranged in the form of a rectangle, one 

 row below the other, measuring IJ by 3i if intended for 

 ordinary slips, or 2 by IJ if for the wider glass. With 

 the dipper, cement the strips together in one compact 

 film, exactly as described for the ribbons, transfer to 



