﻿138 BOTANICAL GAZETTE [February 



tube, 300.6 n long, was seen; hardly any other pollen grains had 

 germinated; (c) only a very small number altogether had germi- 

 nated; (d) no change; (e) a considerable number had formed long 

 pollen tubes, the average length being 1336 n; (/) a considerable 

 number had formed pollen tubes of medium length, but the results 

 were not so good as in (e). 



SERIES VII 



June 5, 19 1 3. — Pollen grains of Warner's King apple collected 

 on May 10, 1913, were put into the incubator at 2i°C. at 4:15 

 p.m. Three cultures were made, namely, (a) 4, (b) 8, and (c) 16 

 per cent sugar solution. The cultures were examined at 12:45 

 p.m. on June 6, with the following results: (a) a considerable num- 

 ber had formed short pollen tubes, some being 50.1 tx long; (b) 

 many had germinated, forming pollen tubes 200.4 long; some 

 were as much as 317.3 ju long; (c) many had germinated, some of 

 the pollen tubes being 300. 6 ju long. 



SERIES VIII 



June 16, 1 9 13. — -Pollen grains of Cox's orange pippin, which were 

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

 at 4:10 p.m., the temperature being 17 0 C. Three cultures were 

 made, namely, (a) 8, (b) 16, and (c) 20 per cent sugar solution. 

 They were examined at 12:45 PM - on J une J 7> the temperature 

 being 18 0 C, with the following results: (a) and (b) a few short 

 pollen tubes were observed in each; (c) the pollen tubes were con- 

 siderably longer than in (a) and {b). The cultures were again 

 examined at 10:30 a.m. on June 19, the temperature being 16 0 C, 

 but no further development of pollen tubes had taken place. 



SERIES IX 



June 26, 1913.— Pollen grains of Bismarck apple collected on 

 May 10 were started in the laboratory at 4: 55 p.m., the temperature 

 being 16? 5 C. Three cultures were made in (a) 16, (b) 20, and 

 (c) 40 per cent sugar solution. The cultures were examined at 

 12:10 p.m. on June 27, the temperature being 16 0 C, with the 



