in Li Hum Martagon: II. Spermatogenesis . 219 
The anthers were left in this solution for one and a half to two 
hours, and then transferred to a -5 % aqueous solution of platinic 
chloride for twenty-four hours. They were then placed in a 1 % 
aqueous solution of platinic chloride for twenty-four hours. 
Flemming's solution [aqueous). 
1 % aqueous solution of chromic acid . 30 c.c. 
1 % osmic acid (aqueous) . . .8 c.c. 
Glacial acetic acid .... 2 c.c. 
The anthers were left in this solution for about two hours, and then 
transferred to an aqueous -5 % solution of chromic acid for eighteen 
hours. 
Chromic acid [aqueous). The anthers were laid in a -5 % aqueous 
solution of chromic acid for eighteen to twenty-four hours. 
After treatment in any of these ways, the anthers were rinsed in 
water, and transferred successively at intervals of about twelve hours 
to 30 %, 50 %, 70 % alcohol, and finally left for several days in 
methylated spirit, changed as it became discoloured. These changes 
were made in the dark when the fixing solution had contained 
chromic acid. 
The anthers were preserved in a mixture of equal parts absolute 
alcohol, glycerin, and distilled water. 
B. EMBEDDING AND CUTTING. 
For anthers fixed in mixtures containing chromic acid or platinic 
chloride, paraffin melting at 32°C. is hard enough. A softer paraffin 
can be used for anthers fixed in absolute alcohol. I was able to cut 
sections 15^ thick from such material embedded in paraffin melting 
at 45 0 C. 
The sections were usually floated on the slide with distilled water, 
and made to adhere by careful drying without cement. But in the 
case of anthers showing the nuclear division within the nearly mature 
pollen-grain, I used a cement of collodion and clove-oil, otherwise the 
sections of pollen-grains would have been washed away. 
Great care must always be taken not to overheat the paraffin- 
ribbon on the slide. If the paraffin approaches its melting-point, the 
sections will be strained and their structure distorted. 
Hand-sections are apt to be broken while they are being transferred 
from a stronger to a weaker solution of alcohol. To avoid this the 
