THE MICROSCOPE. 187 



the slides, but with care in using them the cemented ones will answer 

 every purpose. 



A drop of the fluid to be examined is placed upon the pillar 

 just described, a cover larger than the pillar is placed upon it, when 

 it will be seen that the excess of fluid flows into the annular space 

 surrounding the pillar. Not the least advantage of this new form 

 of slide is that evaporation takes place from the fluid in this annular 

 space, and may go on for a long time without affecting the stratum 

 under examination. 



If desired, the annular space may be filled with oil, and evap- 

 oration thus be entirely prevented. 



Fine Structure of Bone. — G. Broesike has published an ex- 

 tensive memoir on this subject {Archiv. mikr. anat., xxi. 695), of 

 which Eberth has published an abstract, here reproduced. The 

 first part of the paper deals with the limiting-sheaths of the osseous 

 canal system. The sheaths may be isolated by the action of acids 

 on completely macerated bones. They are but slighly pliable, and 

 reproduce perfectly the forms of the canal. They may be destroyed 

 by certain reagents quicker than the basal substance of bone, from 

 which they are therefore different, their substance resembling 

 keratine in the author's opinion. The sheaths are wanting in 

 embryonic and all young bone. The author speculates as to their 

 origin: he thinks they must arise either as a precipitate from the 

 lymphatic fluids, or else by decalcification of the basal substance. 

 (Neither of these views appears probable.) The osseous corpuscles 

 form a continuous net work by the union of their processes. These 

 cells probably have no membrane, and the nucleus soon degenerates. 

 With increasing age, the cells loose their process, and become 

 jagged and smaller, so that there is a space around them; then 

 follows fatty metamorphosis of the protoplasm, and finally complete 

 fatty degeneration, of which the products may be reabsorbed. The 

 author advances the (very probable) hypothesis, that the corpuscles 

 are killed by smothering in carbonic acid, accumulated in parts of 

 the bone remote from the blood-vessels. The basal substance con- 

 sists of uncalcified gelatin, yielding fibrillae, embedded in a calcified 

 cement. The lamellae are formed by primitive layers of fibrillae, 

 which do not intercross and intertwine, although the sets of parallel 

 fibrillae run in various directions. The author distinguishes between 

 regular and irregular fibrillar tissue. — {Fortschr. med., i. 10.) — C. S. 

 M., in Science. 



