128 Gager . — The Development of the Pollinium and 
nuclear phenomena in the formation of the sperm-cells, that 
this study was undertaken, for it is clear that the proper 
interpretation of the structures depends upon a complete 
knowledge of these phenomena. 
Methods. 
Asclepias cornuti was chosen for the basis for the work, but 
comparisons were made with A. phyto/accoides, A. incarnata , 
A. quadrifolia , and A. tuber osa. The material was collected 
at frequent intervals during the months of June, July, and 
August in the summers of 1899 an d 1900. Some of it was 
put up in the field and the rest in the laboratory at different 
times during the day, from 7 a.m. to 7 p.m. After the 
removal of the perianth, the buds were halved to ensure 
more rapid penetration, and placed in Flemming’s chrom- 
osmic-acetic acid solution for twenty-four hours. The material 
was then washed in water for twelve hours, dehydrated, 
bleached, infiltrated, and imbedded in paraffine in the usual 
manner. The sections were cut of various thicknesses, but 
those thirteen and one-half microns thick proved best for 
study. Some of the slides were stained with iron-alum 
haematoxylin, but the safranin-gentian-violet-orange combina- 
tion gave the better results. 
In order to facilitate the handling of the small pollinia they 
were placed in tiny bags of cheese-cloth, closed at the top by 
a small piece of copper wire, one end of which was allowed to 
project as a handle. The pollinia were placed in these bags 
after dehydrating. 
Pollinia were germinated in a 5 per cent, cane-sugar solution 
and placed in the Flemming at intervals of from five to thirty 
minutes during germination. In addition to this, pollinia 
were examined that had germinated on slices of sugar-beet 
kept moist in a Petri dish, and also those that had germinated 
on the stigma. Their behaviour seemed to be the same 
under each of the above conditions. A rather vigorous 
circulation of protoplasm was noticeable in freshly germinated 
pollen-tubes. 
