8 CON KLIN [Vol. XIII. 



As a result of many experiments with almost every one of 

 the common staining fluids, I found that the best method of 

 preparing surface views of the whole egg or embryo was the 

 following: (i) Transfer the object gradually from alcohol to 

 water, (2) Stain from five to ten minutes in a solution of 

 Delafield's (Grenacher's) haematoxylin diluted about six times 

 with distilled water and rendered slightly acid by a trace of 

 HCl. (3) De-hydrate and clear in oil of cedar or xylol. (4) 

 Mount in balsam, supporting the cover glass so as to prevent 

 crushing. By occasionally softening the balsam with a drop 

 or two of xylol and slightly moving the cover glass the objects 

 can be rolled into any position desired. 



By this method wonderfully beautiful surface preparations 

 were obtained, showing with remarkable clearness not only the 

 nuclei and cell boundaries, but also the karyokinetic figures, 

 and in many cases the archoplasmic spheres and centrosomes. 

 One very considerable advantage of this method is that the 

 preparations are permanent — in fact during the first year or 

 two they become better with age instead of degenerating. 

 Most of the preparations from which the figures were drawn 

 are still in existence, and can be consulted at any time. 



I have employed this method with almost as good results in 

 the preparation of surface views of the embryo chick and 

 English sparrow, and also with considerable success on other 

 molluscan eggs and embryos, as well as those of annelids and 

 echinoderms. 



The objects for sectioning were fixed in various fluids, some 

 of which showed certain points of structure better than others ; 

 for general purposes, however, excellent results were obtained 

 by fixing in the picro-sulphuric solution, though the chromatic 

 filaments and individual chromosomes were brought out much 

 more clearly by the use of absolute alcohol, and the spindle 

 fibres and centrosomes were more clearly shown by the use of 

 Flemming's or Hermann's fluid. In all cases the objects were 

 imbedded in paraffin, and the best results were obtained by 

 staining on the slide. On the whole I have found a double 

 stain, consisting of, Delafield's haematoxylin followed by a 

 solution of erythrosine in aniline water, to give the best re- 



