﻿i 9 i6] ADAMS— POLLEN GRAINS 137 



May 19, 1 913. — Pollen grains of Bramley's seedling apple 

 collected on May 10, 1913, and kept dry, were started in the 

 laboratory at 4:45 p.m. on May 19, 19 13. The temperature was 

 i4?5 C. Six cultures were made, namely, (a) water, (b) 1, (c) 2, 

 (d) 4, (e) 8, and (/) 16 per cent solution of cane sugar. They were 

 examined on May 20 at 3:30 p.m., when the temperature was 

 14? 5 C. and the results were as follows: (a) only a few had germi- 

 nated; one had a pollen tube 150.3 n between perpendiculars and 

 there were others still longer; (b) only two short pollen tubes 

 observed; (c) a few had formed short pollen tubes; (d) only a 

 very few had formed short pollen tubes; the longest seen was 81 n 

 long and had a cauliflower-like growth at the end; (e) a small 

 number had formed short pollen tubes; (b) an extremely small 

 percentage had formed short pollen tubes. 



On May 22 at 3:50 p.m., the temperature being i4?5 C, the 

 cultures were again examined, with the following results: (a) only 

 a few had germinated, but they had formed fairly long pollen tubes; 

 one measured 300. 6 /x; (b) a very few had formed short pollen 

 tubes; (c), {d), (e), and (/) same as on May 20; an abundant growth 

 of Penicillium had occurred in these four. This series of cultures 

 was kept continually in the dark. 



SERIES VI 



May 20, 1913.— Pollen grains of Bramley's seedling apple which 

 were collected on May 10 and kept dry were put into the incubator 

 at 22 0 C. at 10: 10 a.m. Six cultures were made, namely, (a) water, 

 (b) 1, (c) 2, (d) 4, (e) 8, (/) 16 per cent sugar solution. The results at 

 4 : 10 p.m. the same day were as follows : (a) and (b) none had germi- 

 nated; (c) one pollen tube was 250.5 ju long, another 384 /x long; 

 several others with pollen tubes of various lengths were observed, 

 but only a small percentage altogether had germinated; (d) only 

 a very few had formed short pollen tubes; (e) a fair percentage had 

 formed long pollen tubes, one being 651 .3 \i long; (/) a considerable 

 number had formed pollen tubes, one being 200.4 n long. 



The results on May 21 were as follows: (a) two pollen tubes 

 were observed but they did not seem to be healthy; (b) one pollen 



