SPECIAL METHODS. 



199. 



34b. Guignard recommends (IV, 166), for bringing out 

 the centrospheres, fixing with alcohol, a 20-30$ alcoholic 

 solution of corrosive sublimate or picric acid, a \% aqueous- 

 solution of corrosive sublimate, a saturated aqueous solution' 

 of picric acid, or a .5$ solution of chromic acid. He has. 

 I II ITI iv 



36. Lilium Martagon. I, tip of the embryo-sac; II, the same, later stage; III 

 d IV, Bolder karyokmetic figures from the same source; a, centrospheres. After 



FIG. 

 an 

 Guignard. 



also used the vapor of osmic acid, but allows it to act only 

 a short time, in order not to lessen the staining capacity of 

 the objects, and then places them in Flemming's solution 

 ( 309) for half an hour to an hour, and 

 then in alcohol. 



For staining the attractive spheres 

 Guignard uses especially haematoxylin ; 

 but he first treats the sections hardened 

 with alcohol with a 10$ solution of zinc 

 sulphate or ammonia alum. He has 

 also treated the preparations success- 

 ively with a dilute aqueous solution of 

 orseillin and eosin-haematoxylin.* The 



* This probably means the eosin-hsematoxylin mixture recommended by 

 Renault. It is prepared, according to Gierke (I, 86), by mixing equal 

 parts of glycerine, containing common salt and saturated with eosin, and a 

 saturated solution of potash alum in glycerine. This mixture is filtered 

 and then an alcoholic solution of haematoxylin or Delafield's haematoxylin 

 ( 314) is added. 



FlG . 37 ._ Nuclei from the fer- 



After Guignard 



