﻿1916] ADAMS— POLLEN GRAINS 141 

 SERIES II 



June 2, 1 9 13. — Pollen grains from a different variety were col- 

 lected on this date. When dry these were elliptical in shape, 

 measuring 37.5X19-5 M- Three cultures were made, namely, 

 (a) 4, (b) 8, and (c) 16 per cent sugar solution. They were started 

 at 4:45 p.m. the same day, the temperature of the laboratory being 

 16 0 C. They were examined at 9:45 a.m. on June 4, the tempera- 

 ture being i5?5 C, with the following results: (a) only a few had 

 produced pollen tubes of medium length, and of these several were 

 tuberculate at the tip; (b) and (c) similar to (a). 



They were examined again at n :oo a.m. on June 5, the temper- 

 ature being 15? 5 C, with the following results: (a) nearly all of the 

 pollen tubes formed were short and of irregular growth, and many 

 of the pollen grains were small and apparently rudimentary; the 

 longest pollen tube seen measured 267 . 2 ju; (b) the pollen tubes 

 were a little more regular in their growth than in (a) ; one measured 

 250. 5 n; (c) similar to (a) ; a pollen tube measured 300. 6 ju. 



SERIES III 



June 6, 1 9 13. — Pollen grains were collected from a seedling 

 strawberry plant on this date. Three cultures were made, namely, 

 (a) 4, (b) 8, and (c) 16 per cent sugar solution. The cultures were 

 started at 4:00 p.m. in the laboratory, the temperature being 

 1 5 ?5 C. They were examined at 3 : 50 p.m. on June 9, the tempera- 

 ture being i4?5 C, with the following results: (a) no proper 

 healthy pollen tubes were observed; (b) numerous long pollen tubes 

 were observed, one measuring 1169*1; (c) two short pollen tubes 

 were seen, but the vast majority had behaved like those in (a). 



SERIES IV 



Pollen grains were collected on June 2, 19 13, and started in 

 10 per cent sugar solution at 5 : 00 p.m. on August 6, the temperature 

 being 16 0 C. At 4:45 p.m. on August 7 none had germinated. At 

 5:00 p.m. on August 8 the result was the same. 



Loganberry 



Dry pollen grains elliptical, 43 . 5X 22 . 5 ju. June 2, 1913. Pollen 

 grains were collected on this date and started in the laboratory at 



