The Microscope. 337 



Fat-Crystals. — In examining adipose tissue long removed from 

 the body, or, occasionally, directly after removal, a few vesicles will 

 be found, containing crystals of the fatty acids. They resemble 

 delicate burrs, and are composed of fine, needle-shaped crystals. If 

 they are not to be found in the specimens at hand, it is only neces- 

 sary to mount a small piece of tissue in glycerin and set it away for 

 a time, when they will gradually form. 



Yellow Elastic Tissue. — Take a longitudinal snip from the 

 ligamentum nuchse of the ox. Allow it to soak in a moderately 

 strong solution of sodium chloride in water (about 15 per cent.) for 

 a few days, tease out in glycerin and examine. The fibers are 

 thick, branched, and communicate with each other. The free ends 

 will be found curled up, showing their elasticity. No nuclei are 

 discernible. With a moderately high power, the fibers will be 

 found to have delicate transverse markings at intervals. The cause 

 of these is unknown. Elastic tissue is seldom found in a pure state, 

 being mixed with more or less white fibrous tissues. The white 

 elastic tissue mentioned in the last lesson, is quite identical with the 

 yellow variety, although of much finer texture and color. Elastic 

 tissue occurs in a comparatively pure form in the ligamentum nuchse 

 and ligamenta subflava of the vertebra, in the walls of the bronchi 

 and connecting the laryngeal cartilages. It is mixed with white 

 fibrous tissue in the serous membranes, subcutaneous tissue, inter- 

 muscular septa, etc. Elastic tissue does not always occur as bundles 

 of fibers. In the blood-vessels it takes the shape of a membrane, as 

 it does in Bowman's and Descemet's membranes of the cornea and 

 the basement membranes underlying many epithelial surfaces. 



EDITORIAL. 



1\ /TANY professional men who use the microscope as an auxiliary 

 -^ -*- to their work never succeed in making a collection of objects 

 for future reference and study, partly because they are too busy, and 

 paitly because they do not consider the object to be mounted as 

 worthy of preservation. The meagre collections of such individuals 

 will consist of examples of rare specimens in their work, hardly as 

 valuable for study as a larger number of the every-day objects. It 

 is the unexpected which often happens. How often it occurs to con- 

 stant workers with the microscope that a specimen, hardly deemed 

 worthy of permanent preservation, is extemporaneously mounted in 



