The Microscope. 375 



mounting, and date, are filled in with ink. At the upper left hand 

 is placed the se7'ies of the slide in Roman numerals, while just 

 below it, in Arabic numerals, is the number of the slide in 

 the series, thus: "Series XVI, Number 1." This is also done 

 with pen and ink. On the label on the other end of the slide 

 should be written the kind of section — that is, transection, longi- 

 section, etc.— the age, and kind of embryo, and finally the 

 hardening, staining and mounting agents which have been 

 employed. 



For securing these labels to the glass, Le Page's glue will be 

 found excellent. As these labels project sufficiently above the 

 cover-glass to protect it from injury, several of the slides may be 

 piled together and set aside while drying. 



While mounting a series of slides, I am accustomed to note the 

 series and number of slide on the back of the latter with ink, so 

 that labeling may be postponed until the series is completed. 



For a slide cabinet, I have had made a stong pasteboard box 

 with hinged front, holding ten pasteboard trays. Each tray is 

 divided into three compartments, which hold nine slides each, thus 

 giving twenty-seven slides to the tray and two hundred and seventy 

 to the box — a number which the beginner will be long in making. 

 For it must be remembered that all eggs put to incubate will not 

 prove fertile, neither will all slides prepared be found worth 

 preserving. 



A COURSE IN ANIMAL HISTOLOGY. 



FRANK W. BROWN, M. D. 



SIXTH PAPER. 



RETIFORM Tissue. — Take a small piece of umbilical cord at the 

 fifth month (although a cord at any stage of its development 

 may be used), and harden in MliUer's fluid, after which it is to be 

 placed in 95 per cent, alcohol for a time. It can then be embedded 

 in celloidin and sectioned. If the worker is not familiar with the 

 use of celloidin he may proceed as follows : Put the specimen in 

 water until the alcohol has been withdrawn. Now make a solution 

 of gum arable in glycerin to the consistency of thick honey. This 

 can best be done by first making a stiff paste of the gum with water 

 and then adding the glycerin. The specimen is now placed in this 

 solution until it becomes thoroughly infiltrated and sinks to the 

 bottom, when it is removed to stronger alcohol. The alcohol removes 

 the glycerin, for which it has an affinity, and precipitates the gum 



