1895.] MICROSCOPICAL JOURNAL. 237 



Sections. — Select the pig's liver, because the lobules 

 are clearly circumscribed by connective tissue, especially 

 at the surface, from which take the pieces to be sec- 

 tioned. To prevent pressure of the part to be cut, re- 

 moA'e a cube by a very sharp razor with no pressure of 

 the fingers and use it for sectioning. 



Fixing. — We do not recommend alcohol, but, if u.-^ed, 

 proceed thus : A cube of one half centimetre is put in 

 absolute alcohol for twenty-four hours. Wash in water 

 for half an hour, transfer to gum (twenty-four hours), 

 to 95° alcohol (twenty-four to forty-eight hours). Sec- 

 tion, stain in picro-carmine, mount in glycerine. But 

 osmic acid is the fixative par excellence for the liver. 

 Take a strip 1 mm. long, put it in 3 or 4 cc. of 1 per 

 cent osmic acid for twenty-four hours.. Wash in water 

 for twelve hours, harden in gum and alcohol. Section, 

 free from gum, stain in alum carmine and mount in gly- 

 cerine. Picric acid may be used for these sections to 

 show the glycogenic material. Apiece 1 mm. on a side 

 is placed, still warm, in 50 grammes of the aqueous 

 solution of picric acid for twenty-four hours. Harden 

 in alcohol and put the secti<.)ns in water till the yellow 

 color is gone. Stain. Ammonia bichromate (2 per 

 cent) is very useful for fixing small pieces one half to 

 one centimetre thicl^: Use a large amount of the solu- 

 tion (150 to 200 cc), and renew it once or twice. After 

 a week's sojourn in the bichromate, wash in water for 

 twenty- four hours, harden in alcohol and gum. The 

 sections, freed from gum, should be stained in hemat- 

 oxylin and eosine and mounted in balsam. 



OajriUary Injection. — The vascular network may be 

 studied in the liver of the rat. After injection, treat a 

 small piece by bichromate for eight days, then by gum 

 and alcohol, make sections transversely and pcrjiendicu- 



