2OO BOTANICAL MICROTECHNIQUE. 



interior of the centrosphere is stained deep red by this 

 treatment. 



For mounting such preparations, Guignard recommends 

 especially glycerine-gelatine and a 10$ solution of chloral 

 hydrate thickened with gelatine. The latter has the advan- 

 tage of clearing the preparations, but gradually destroys 

 most dyes. 



3480. Guignard has succeeded in bringing out the attrac- 

 tive spheres especially in various sexual cells. In the grow- 

 ing stamen-hairs of Tradescantia he also succeeded by 

 treating them successively with osmic acid vapor, Flem- 

 ming's chrom-osmic-acetic acid mixture, and alcohol, and 

 then staining with a mixture of fuchsin and methyl green. 

 If this mixture is rightly prepared, the centrospheres are 

 colored bright red in the pale red protoplasm. 



348d. Hermann (II, 583) has recently used the following 

 method for making visible the centrospheres and the radi- 

 ating structures around them, in animal cells. The ob- 

 jects, fixed with platinum-chloride-osmic-acetic acid and then 

 reduced with wood-spirit in the manner described in 313, 

 are placed whole in the dark in a haematoxylin solution con- 

 taining one part haematoxylin, 70 parts alcohol, and 30 parts 

 water. They remain in this solution 12 to 18 hours, are 

 then treated for the same time, also in the dark, with 70$ 

 alcohol, and are then imbedded and sectioned with the 

 microtome. The sections are then extracted with a solu- 

 tion of potassium permanganate so dilute that it has a bright 

 rose color, until they have an ochre-colored appearance. 

 After rapid rinsing in water, the manganese peroxide is dis- 

 solved out with a solution of one part oxalic acid and one 

 part potassium sulphate to 1000 to 2000 parts of water, and 

 the sections are then stained for three to five minutes with 

 safranin. The attractive spheres and the structures sur- 

 rounding them appear deeply blackened, while the nuclear 

 elements have a bright red color. 



How far this method can be used with success for plant- 

 cells remains to be shown. But I will remark that the 

 methods used by Flemming on animal cells with the best 



