180 The Microscope. 



with the formation of fibrin to produce clotting. To demonstrate 

 them, mix a little blood with a Ifo aqueous solution of osmic acid, 

 cover quickly and examine. A trained eye and good lenses will 

 discover them. They require further study. 



Other elements in the blood. Besides the bodies above described 

 other microscopical matter is occasionally found in the blood. 

 Small fat granules and other food substance, may be discovered 

 after eating. "Phantom" corpuscles (the skeletons of red cor- 

 puscles ) ; small pieces of red or white cells, particles of foreign mat- 

 ter of various sorts; all these may be found but hardly need descrip- 

 tion. 



EUDIMENTS OF PRACTICAL EMBRYOLOGY.* 



W. p. MANTON. 

 STAINING. 



§ 8. Embryos may be stained in toto, or after the sections 

 have been placed on the slide. The former method will be found the 

 simplest and most convenient for general practice. Either of the 

 carmine solutions, or the hamatoxylin, may be used, but the borax 

 carmine has given the best results in my hands. If it is desired to 

 stain the embryo at once after hardening and placing in 70 per cent, 

 alcohol, it must first be washed in water (if it is a picric acid speci- 

 men, but not if it has been hardened in chromic acid), and then 

 placed in the carmine, where it should remain for several hours, 

 according to the size of the embryo. It is then washed again in 70 

 per cent, alcohol made slightly sour by the addition of a drop or two 

 of concentrated hydrochloric acid. Thus stained, the embryo may 

 be preserved in 95 per cent, alcohol, ready for embedding at some 

 future time. 



INFILTRATING, f 



§ 9. A. Before sections of the delicate embryo can be made, it 

 must first be infiltrated and embedded in some material which 

 will hold it fii-mly without injuring its tissues. For this purpose, 

 paraffine has been found to be the best substance. The specimen is 

 first placed in absolute alcohol for several hours, until it is thoroughly 

 dehydrated, and then in a vial of chloroform where it may soak for 

 some time longer. It is then transferred to a watch glass contain- 

 ing chloroform and fine shavings of hard and soft paraffine (1 to 5), 



♦Copyrighted 1888. 



tThere are many methods given for infiltrating (he embryo, but the following has been 

 found satisfactory in the author's experience. Of course, the general technique once 

 learned, no worker will pin his practice to one method alone. See Dr. Minot's article on 

 this subject in the May Microscope. 



