2-J54 Journal of Applied Microscopy 



When wanted for cutting, the tissue is wiped dry with a clean cloth, a thin 

 layer of celloidin is shaved off, and the piece immersed in six per cent, celloidin 

 several minutes, then mounted on a block, and hardened in chloroform. 



The only disadvantage of the method is the time taken to completely embed 

 an object, at least twelve days, but one is amply compensated for this by the 

 many advantages which the method affords. Among these may be mentioned 

 the following : 



I. Many tissues which would suffer shrinkage if transferred abruptly from 

 thin to thick celloidin, may be embedded without injury. 



II. Owing to the gradual method of advancing from weaker to stronger 

 solutions, the ultimate concentration of the solutions may be increased much 

 beyond that ordinarily employed. 



III. More perfect infiltration of the object is attained. 



IV. The resulting block of celloidin is of firmer and more uniform consist- 

 ence, enabling one to cut much thinner sections, without tearing or separation. 



V. The preservation of blocks of celloidin in alcohol glycerine permits of 

 the storage of large quantities of class material in much smaller space than 

 would be required if each piece were mounted separately on a fibre block. 

 Morover, this method admits of the trimming of the celloidin blocks after hard- 

 ening in chloroform, thus saving a great deal of celloidin for subsequent use. 



VI. With several blocks of compressed fibre for mounting, one can do a 

 large amount of work. 



I have found the following method very convenient for keeping a record of 

 tissues. 



Each piece of tissue on removal from the animal is entered in a book by 

 number, together with name of animal and fixation. On taking each piece from 

 the twenty per cent, celloidin, a small tag of stiff paper, with number in lead 

 pencil, is attached, and embedded with it, and the whole dropped into chloroform 

 to harden. The tissue is then preserved in alcohol glycerine until wanted. 

 Hull I>aboratory of Anatomy, University of Chicago. CharlES H. Miller. 



A Method for Preparing Sections of Cancellous Bone. 



Much difficulty is experienced in grinding sections of dry bone and tooth 

 (especially of cancellous bone) by the usual method of embedding the material 

 in cork or holding on the grindstone with the finger. By these methods it is 

 very difficult to grind all parts of a section to the same thickness, the piece of 

 material cannot be held firmly in one position ; thus the soft parts of the tissue 

 are ground thin before the more compact, and a section in the desired direction 

 (as a direct transverse section, longitudinal section, etc.) is difficult to secure. 



The following method has proved very satisfactory in preparing sections of 

 bone, tooth, shell, and especially cancellous or spongy bone : 



With a tine saw cut sections (about one-half mm. in thickness) of cancellous 

 bone tissue from a well prepared piece of bone, bone which has been macerated 

 until all fatty substance is removed, then allowed to dry. Rub the section on a 



