292 Journal of Applied Microscopy. 



Noticing the scale-like structure of the fiber, as shown by the sketch, let us 

 enquire into the peculiarities of these scales. For this purpose place a number 

 of Merino fibers upon a glass slide, and cover them with another slide of equal 

 thickness. Apply one or two drops of (H., SO^) sulphuric acid (c. p. S..G. I'lS") 

 to the edge of the glass cover, so that the liquid will be drawn between the 

 glasses by capillary attraction. Place the slide under the microscope, and a 

 one-inch objective will serve to show the changes the libers will undergo from 

 the action of the reagent. As soon as the sulphuric acid is drawn over, and 

 impregnates the fibers, they are observed to swell or expand slightly, and trans- 

 verse markings become apparent. When no more changes occur, and the 

 reaction thus seems complete, the slide should be removed and heated with an 

 ordinary alcohol lamp until it becomes perceptibly warm to the hand. It should 

 then be replaced upon the stage of the microscope, and the changes noted. It 

 will be seen that the simple heating of the slide has caused the transverse 

 markings to become decidedly more prominent and the serrations at the edges 

 of the fibers much more distinct. Thin scales (epidermal epithelia) begin to 

 separate slowly by curling up along their edges, and these in reality caused the 

 transverse markings. They now separate from the main structure, and when 

 entirely free, show a tendency to curl themselves up and roll into little spheres, 

 totally unrecognizable, and permitting of no further profitable study. At present 

 there is no means of determining the form of these scales in this separated, free 

 condition, but as studied while in the act of separating from the fiber, they are 

 unequal, distorted, very transparent, and extremely thin. ha\ing a thickness of 

 only 0.0014 millimeters. There can be little doubt that nature des'igned these 

 little scales to give wool fiber its peculiar felting property, a characteristic upon 

 Avhich the value of the staple for manufacturing purposes so largely depends. 



Ernst Fahrig, Ph. D., William P. Wilson, Sc. D., 



Chief of Laboratories. Director. 



The Preparation of Ground Sections of Teeth and Bone. 



Few preparations for the microscope demand the painstaking attention to 

 manipulative details that is required for the successful preparation of fine 

 sections of teeth and bone. Many short notices have appeared in books and 

 journals on rapid methods of making these sections by hand ; rubbing them 

 down on glass, stone, and in other ways. I have tried many of these and do 

 not find that I can get good results. To those who simply want one or only a 

 few sections, I would say, you can get them from a dealer far cheaper than you 

 can make them. To the student, or those who desire to make many sections, I 

 offer the method I use, to which I have drifted after large experience in making 

 these preparations. 



Apparatus. — A grinding machine, suitable laps of copper, lead, and stone, 

 grinding powders, a chemist's wash bottle, a small metal table, hardened balsam. 

 My grinding machine is home-made. It is a large Swiss jeweler's lathe, fitted 



