AND HOW TO USE IT. Ill 



Bleu de Lyon ; the nuclei of the gland-cells or the organ of Bojanus, 

 hardened in alcohol, come out emerald green, the protoplasm is 

 unstained ; cell membranes and cilia are stained red. A transverse 

 section of the edge of the foot oi Afiodonta from an alcohol specimen 

 should be washed in distilled water, drawn quickly through a dark 

 solution of Rose Bengale, then washed in pure distilled water, and 

 placed for some seconds in Iodine Green, washed again in dis- 

 tilled water, and placed for about five minutes in absolute alcohol 

 to fix the colour and remove possible excess ; the sections are now 

 drawn two or three times through a solution of Bleu de Lyon 

 with two parts of absolute alcohol, and three of distilled water, 

 transferred to absolute alcohol, clarified in oil of aniseed and 

 mounted in dammar. The result will well repay all the trouble of 

 preparing. 



Stains for Fresh Tissues of Vertebrata :— For fresh or recently 

 dead tissue and thin parts capable of ready examination by trans- 

 mitted light. The stain recommended is Mayer's Violet Blue of 

 Bindschedler and Busch (Bale), in about the proportions of one 

 gramme to 300 c.c. of \ per cent, solution of salt. The mesentery 

 is very well stained by this reagent, the vascular system being very 

 clearly brought out^ while the connective tissue is rendered pale 

 red ; this is best seen in one of the taches laitenses of Ranvier. 

 The piece should be first shaken up in a test-tube with some of 

 the \ per cent, salt solution, then spread out smooth on a glass 

 plate with a brush covered with a drop of staining fluid for ten to 

 thirty seconds, then removed with a bristle and washed with salt 

 solution for examination. The method is preferable to injection, 

 from the distinctness with which the vessels are brought out, 

 the definition of the structure of their walls, the superior rapidity 

 and simplicity, and the prevention of misleading appearances. 

 Specimens too deeply stained can be made paler by washing in a 

 \ per cent, salt solution ; specimens which are quite fresh require 

 a rather lengthy staining, viz., from half to one minute. Another 

 very good object to which to apply this method is the hyaloid 

 membrane of the frog's eye. It is also especially useful for ex- 

 hibiting smooth muscular fibres, as found in the serous mem- 

 branes of the pelvis, abdomen, and thorax. 



