Coral 



GROUND SECTIONS 



87 



in tlie balsam; therefore washing in water 

 will remove it. 



The section must now l)e mounted on 

 the slide which it is finally to occupy, but 

 this is done in exactly the opposite manner 

 to that described in the last example, in 

 which the shde was covered in balsam and 

 the object pressed to it. In this case the 

 section must be placed on a flat surface, a 

 slide warnred rather above the melting 

 point of the balsam and pressed down on 

 to the specimen so as to melt the minimum 

 possible quantity of balsam to permit per- 

 fect adherence. Only in this manner can 

 one avoid disturbing the soft parts. The 

 other side of the section is now ground 

 down, smoothed, and polished exactly as 



described in the last examj^le. It will, how- 

 ever, be much easier to estimate the thick- 

 ness of a section of this type, for one can 

 always observe the soft parts under the 

 microscope. When the section has become 

 sufficiently thin, it is only necessary to 

 ])lace a drop of natural l)alsam on top, ap- 

 ply a coverslip, and warm the whole while 

 applying jiressure. 



Though this description has api^fied to 

 the preparation of a coral, it may equally 

 well be applied to the production of sec- 

 tions of bone with the bone marrow and 

 blood cells retained in position. Those who 

 prefer to grind their sections on oilstones 

 with an oil lubricant should consult the 

 description of Henrichi 1916 (4349, 6:45). 



