POLLINATION OF THE MANGO. 13 



difficult of all to germinate. The percentage of grains which sent 

 out pollen tubes varied from to a little more than 50, but in the 

 vast majority of the cultures would not average above 10 or 15 per 

 cent. No pollen tubes developed to a length exceeding seven times 

 the diameter of the pollen grain, and commonly they did not exceed 

 four or five diameters. Without going into detail regarding the 

 cultures, of which about 300 were made, it can be said that the 

 germination of all varieties was very poor. While the percentage 

 of germination was higher in some varieties than in others, it varied 

 in the same variety upon different days, though the conditions were 

 as nearly similar with regard to culture medium and temperature as 

 it was possible to keep them. The percentage of germination and 

 the vigor of the pollen tubes were greatly inferior to those obtained 

 in cultures of the feijoa (Feijoa sellowiana), the lumbang (Aleurites 

 rnoluccana), or several other plants which were tested. It has been 

 pointed out by Prof. E. J. Kraus, however, that pollen germinations 

 made under moist-chamber conditions do not necessarily indicate 

 the germinability of the grains on the stigmas under optimum 

 conditions. 



THE PRODUCTION OF FRUIT. 



The stigmas, as has been shown, receive no pollen in more than 

 half the instances; and of those cases where they are pollinated, in 

 comparatively few are there more than one or two grains upon each 

 stigma. 



Under these conditions it was thought that the production of 

 fruit might be increased noticeably if the stigmas were pollinated 

 more abundantly ; with ample pollination, even if some of the pollen 

 grains were defective, a few capable of developing pollen tubes and 

 reaching the ovum should reach each stigma. Working on this 

 theory, a number of hand pollinations were made. 



On a 6-year-old tree of the Bennett variety at the E. B. Douglas 

 place, Buena Vista, Fla., five panicles of flowers were selected for 

 hand pollination, and on two days, April 28 and May 1, 1915, pollen 

 from the same tree was applied to all the fresh stigmas on each pan- 

 icle. The exact number pollinated on each panicle was as follows : 



Panicle No. 1 30 stigmas. 



Panicle No. 2 25 stigmas. 



Panicle No. 3 31 stigmas. 



Panicle No. 4 25 stigmas. 



Panicle No. 5 51 stigmas. 



These were not all of the perfect flowers on each panicle, but it was 

 thought advisable to pollinate only those stigmas which appeared 

 to be fresh and in a receptive condition at the time the work was 

 done. No fruits were carried on any of these panicles, though on 

 May 21 about 60 well-formed fruits were counted on other panicles 



