﻿I 4 2 BOTANICAL GAZETTE [February 



4:45 p.m., the temperature being 16 0 C. Three cultures were 

 made, namely, (a) 4, (b) 8, and (c) 16 per cent sugar solution. 

 They were examined at 9:45 a.m. on June 4, the temperature 

 being i5?5 C, with the following results: (a) many had germinated 

 and formed long pollen tubes; (b) most of the pollen grains had 

 attempted to germinate, but the pollen tube, as a rule, was short, 

 being no longer than the diameter of the pollen grain, and irregular 

 and tuberculate. A few had formed fairly long, properly devel- 

 oped tubes; (c) same as (b ). 



At 10:45 A.M. on June 5, the temperature being i5?5 C, they 

 were again examined: (a) a pollen tube measured 1052. 1 /x long; 

 (b) these had made little further growth from the previous day; 

 a pollen tube measured 250. 5 ju; (c) similar to (6) for the most part; 

 a pollen tube was 467 . 6 ft. 



An attempt was made on August 6 to germinate some of the 

 pollen grains collected on June 2 in 4 per cent sugar solution, 

 but no pollen tubes developed. 



Raspberry 



Dry pollen grains elliptical, 33X21 fx, globular when wet. On 

 June 5, 1913, pollen grains were collected and put into the incubator 

 at 21 0 C. at 4:15 p.m. Three cultures were made, namely, (a) 4, 

 (6) 8, and (c) 16 per cent sugar solution. They were examined 

 at 12:45 p.m. on June 6, with the following results: (a) contents 

 of the pollen grain had protruded slightly, but no proper pollen 

 tubes were observed; (b) mostly similar to (a), but in a very few 

 cases fairly well developed pollen tubes were found; (c) a consider- 

 able number had formed pollen tubes, one of which measured 

 317.3 /i between perpendiculars. An attempt was made on 

 August 6 to germinate some of the pollen grains collected on 

 June 5 in 16 per cent sugar solution, but without success. 



Black currant 



Pollen grains when dry spherical, 30 p in diameter, in water 

 spherical, 42 fx in diameter, with a number of germ pores. 



