127 



in the fluids already mentioned and, iu addition, in Foa's blood 

 mixture and in absolute alcohol; and lastly, in the oldest stages, 

 the uterus has simply been opened and the placenta preserved, 

 beiug always, when osmic mixtures have been used, first bisected. 



It should be noted that a certain amount of distortion is un- 

 avoidable; if on the one hand the material is preserved in toto the 

 violent contraction of the muscularis unduly compresses the tissues 

 inside, on the other hand when the uterus is opened before pre- 

 servation, the cut edges of the uterine wall curl up, and in so 

 doiug pull the edges of the placenta out of shape; heuce the 

 importance of employing material preserved under both conditions. 

 Finally I have had recourse to the examination of perfectly fresh 

 material, teased up on the slide and observed in 0.4 per cent salt 

 solution to which a little methylene blue is added. In these cases 

 control pieces of material have always been taken from the same 

 doe and preserved in the ordinary manner. 



For staining I have used borax-carmine foliowed by picro- 

 nigrosin, licht-grün, saure-violett and picric acid, or picro-indigo- 

 carmine; Ehrlich's haematoxylin, or iron haematoxylin foliowed 

 by orange G, eosin, or acid fuchsin and picric acid; safranin fol- 

 iowed by licht-grün, or saure-violett; gentian violet foliowed by 

 eosin or orange G; Maun's methyl-blue-eosin, and occasionally 

 methylene blue. 



All of these stains have their values, but for general purposes, 

 after sublimate material, borax-carmine, foliowed by picro-indigo- 

 carmine, is difficult to surpass. 



My work has been mainly done in Oxford, in the Department 

 of Comparative Anatomy; and I have to express the obligations 

 I am under to the Linacre Professor, Professor Weldon, for the 

 assistance I have received in the preparation of sections and in 

 other ways. I am very much indebted for friendly advice and 

 criticism, as well as for many valuable suggestions, to Dr. Bourne, 

 Dr. Haldane, Dr. Ritchie, and Mr. Ramsden; to Dr. Ritchie in 

 particular for his generous permission to use the micro-photogra- 

 phic apparatus in the Pathological Laboratory. ï am greatly obliged 



