METHOD XVIII. 



METHODS FOR THE TREATMENT OF EMBRYOS. 



Some suggestions as to the fixation and preservation of human 

 embryos and foetuses. 



The most valuable embryonic material, and that most desired 

 by neurologists as well as embryologists, is that of the human 

 subject. As yet our knowledge is badly deficient concerning 

 many points in the development of the human embryo, and espe- 

 cially so concerning some of the early stages. This is due, of 

 course, to the difificulty with which human material is obtained. 



Opportunities to obtain human embryos are offered almost 

 exclusively to the physicians, and quite often these opportunities 

 are sadly neglected. Most often, perhaps, the material is not 

 saved, either because the physician does not realize its value, or 

 because he does not know how to treat it or is not prepared to 

 do so. 



Most of the fluids recommended in the books for the fixation 

 of embryos contain ingredients which the physician not only 

 does not usually have in his office, but which are not obtainable 

 from the stock of the ordinary drug store. 



The object of these suggestions, therefore, is not to give such 

 fluids and procedure as are considered absolutely the best t>y 

 embryologists for the fixation and preservation of embryos, but 

 to mention such efficient fixing fluids as the physician can easily 

 obtain from his druggist or can quickly make up from his own 

 stock of drugs, and which allow as much latitude as possible in 

 the subsequent treatment for the preservation of the specimens. 



It is presumable that every physician has, or can quickly 

 obtain, the bichloride of mercury, potassium bichromate, commercial 

 4.0 per cent, formaldehyde, chloroform, acetic acid, strong commercial 

 alcohol, and distilled water. From these reagents he can make the 

 following excellent and inexpensive fixing fluids : 



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