﻿igi6] ADAMS— POLLEN GRAINS 139 



following results: (a) two long pollen tubes were observed; (b) a 

 few were beginning to germinate; (c) no pollen tubes were observed. 



On June 28 at 10:35 a.m., the temperature being i6?5 C, the 

 results were as follows: (a) a few more were beginning to germi- 

 nate; (b) a few had formed pollen tubes; (c) no pollen tubes were 

 observed. On June 30 at 10:30 a.m., the temperature being 18 0 C, 

 no further growth in any of the cultures had taken place. 



series x 



August 6, 1913. — Pollen grains of several varieties of apple 

 which were collected on May 10 and kept dry were started at 

 5:00 p.m., the temperature of the laboratory being 16 0 C. The 

 following were the varieties and strengths of sugar solution used: 

 (a) Nelson 4 per cent, (b) Wyken pippin 16 per cent, (c) Warner's 

 King 20 per cent, (d) Bramley's seedling 4 per cent, (e) Duchess of 

 Oldenburgh 16 per cent, (/) Bismarck 20 per cent, (g) Cox's orange 

 pippin 16 per cent. The cultures were examined at 4:45 p.m. on 

 August 7, the temperature being 16 0 C. The results were as 

 follows: (a) two short pollen tubes were observed; (b) and (c) no 

 pollen tubes; (d) several short pollen tubes; (e), (/), and (g) no 

 pollen tubes. 



They were examined again at 5:00 p.m. on August 8, the 

 temperature being 16 0 C, with the following results: (a), (b), (c), 

 (d), and (e) no change; (/) a considerable number of short pollen 

 tubes were seen; (g) no change. 



Pear 



The variety used was Doyenne du Cornice. The dry pollen 

 grains were elliptical and measured 42X25.5 ju. 



May 29, 1913. — Pollen grains which were collected on May 27 

 were started at 11:05 A.M. in the incubator at 21 0 C. Three cul- 

 tures were made, namely, (a) 4, (b) 8, and (c) 16 per cent sugar 

 solution. They were examined the same day at 4 : 40 p.m., with the 

 following results: (a) many had germinated, some of the pollen 

 tubes being 551 . 1 n long between perpendiculars; (6) several had 



