The Hypophysis Cerebri. 303 



alcohol, 50^1;', 70 ?o, 90%, and had been in ordinary com- 

 mercial alcohol several years when they came into m}' pos- 

 session. No especial pains had been taken to fix or harden 

 them, but the entire uterus, without being opened, had been 

 in each case placed in alcohol. 



The uterus was opened, and the embryos, still within the 

 amnion, were taken out and placed in equal parts of sulphuric 

 ether and 95 per cent, alcohol for several da^^s. They were 

 then transferred to a thin solution of Schering's celloidin in 

 equal parts of sulphuric ether and 95 per cent, alcohol, where 

 thev remained for several davs. The embryos were then 

 transferred to a thick solution of celloidin, prepared as before. 

 After several days of this treatment, the embr3-os were im- 

 bedded on cork in the usual manner, and the cork placed in 

 50 per cent, alcohol. 



The embryos were allowed to remain in the several solu- 

 tions mentioned much longer than is usually deemed necessary, 

 in order to insure a thorough impregnation of the embryo by 

 the imbedding material. 



After being thus imbedded, the embr^-os were sectioned 

 in a large Bausch & Lomb microtome, the sections being 

 made su'si) of an inch thick. The sections were then stained in 

 Grenacher's hcematoxylin. 



After the sections had been stained, they were cleared w-ith 

 oil of bergamot, and m.ounted in Canada balsam, each section 

 on an ordinary 1x3 slide. Care was taken to place them 

 in the same relative position. After the entire number of 

 sections from one embryo had been mounted, the slides w'ere 

 carefully arranged in serial order, labeled, and the labels num- 

 bered serially. 



This method necessitated the expenditure of a vast amount 

 of time, which might have been avoided by using any one 

 of the various methods of serial sectioning. Moreover, the 

 ha^matoxylin readily stains celloidin, and it was impossible to 

 remove the stained celloidin from the sections by the use of 

 oil of cloves, and still retain the cells in their relative positions. 



