STUDIES tN POLLEN, WITH SPECIAL REFERENCE TO LONGEVITY 763 
Germination of corn pollen 
Great difficulty was experienced in the first. attempts to germinate corn 
pollen. There was no germination in water, altho Jost (1905) claims 
to have succeeded in obtaining it. Various kinds and concentrations 
of sugar were tried unsuccessfully. Pieces of stigma and decoctions of 
stigmas had no effect. Occasionally, several grains developed short germ 
tubes, but there was no general germination. 
Later experiments were more successful. A 20-per-cent germination 
was obtained in 10-per-cent cane sugar plus 0.7-per-cent agar, as recom- 
mended by Andronescu (1915). By varying the concentration, even 
better germination resulted, as is shown in table 4: 
TABLE 4. GERMINATION OF CoRN POLLEN 
Medium 
Germination 
Agar + Cane sugar 
Per cent Per cent Per cent 
1.0 TUG (0) oer eine rae as OBE RN SE ev a a 56 
0.7 TUS 0) ee ject ae RNR a a ee Cia 62 
0.7 PAD) SD) Sek OMe Bieta scar ene are CC 18 
0.5 I /ipe Nhe Pse neseree eee eye nel eo bates cae ee, en k 30 
0.5 TUE} (0) 4 Nas AI Se Se UE Are ee 3 
Germination is so rapid that after two or three minutes the protrusion 
of the tubes may be observed. The subsequent elongation was slower. 
Protoplasmie streaming was plainly visible in the germ tubes. After 
twenty-four hours, the germ tubes ranged in length from one to seven 
times the diameter of the grains. 
Good germination was not obtained consistently. At times, the results 
from a certain concentration of solution were excellent; again, the same 
strength of solution failed to induce germination. Apparently the water 
relations were very delicate and the concentration had to be exactly 
correct before germination could take place. This is a common difficulty 
with the pollen of Graminae, according to other investigators (Anthony 
and Harlan, 1920). Martin (1913) found this to be true also of the 
pollen of Trifolium pratense. 
