44 



The Journal of Heredity 



During this operation he is assisted by 

 the first man, who holds the leaf away 

 so that the bag may be pulled well 

 down over the shoot. The bag then 

 is fastened in place. 



The bag may be tied in place with 

 string or wire, or may be fastened with 

 paper clips by ]jrin;4'.ng" the two front 

 corners of the bag (toward the plant) 

 forward around the stalk, folding them, 

 and clipping. This method is shown in 

 Figure 18. which illustrates a plant on 

 which pollination has been completed. 

 The use of clips has several advan- 

 tages. The corners of the l)ag not 

 clipped accommodate the growth of the 

 shoot so that little further attention 

 is required. There also is less dam- 

 age from rain, as the attachment to 

 the stalk helps to hold the ear erect 

 with the bag over it like a tent. 



The time required for the operation 

 as described is about the same as would 

 be needed to apply pollen from the 

 previously bagged tassel under the 

 older method. Consequently the time 

 otherwise required for bagging the 

 tassel is saved. Two men made 380 

 pollinations in six hours, under favor- 

 able conditions during the past season. 

 This is something more than sixty per 

 hour or one pollination per minute. 

 The average, however, was about forty- 

 five pollinations per hour for two men. 



Pollinations may be made at any time 

 of the day, as shedding of pollen does 

 not have to be in progress at the time 

 of bagging. It is necessary, however, 

 to know that the tassel will shed pol- 

 len later on. In this connection, it has 

 been found that tassels will shed little 

 or no pollen if they are pulled more 

 than a few hours l)efore shedding be- 

 gins. If pulled after the central spike 

 has begun to shed abundantly they may 

 c(jntinue to shed for four or five days 

 under favorable conditions, and this is 

 the best time to pull them. 



Bottles of about one ounce capa- 

 city with a mouth al)out three-quarters 

 of an inch in diameter proved the 



most satisfactory of several kinds tried. 

 1 hese were obtained at prices ranging 

 from two to three cents each. They 

 were left on the stalks about four days 

 and then were collected for further 

 use, so that only enough were needed 

 to take care of four or five days' polli- 

 nations. Some tassels will shed satis- 

 factorily without being put in water. 

 The cost of the bottles is small, how- 

 ever, and it is safer to use them 

 in all cases. The bottles may be at- 

 tached to the stalk with copper wire 

 (about No. 23 B&S) twisted first 

 around the neck of the bottle and then 

 about the stalk. The bottles also may 

 be hooked in place by means of a 

 stifif wire fastened to the neck and 

 properly bent. 



This method was used satisfactorily 

 in making over 7,000 self-pollinations 

 in 1922. A representative sample of 

 the ears obtained is shown in Figure 

 18. Both yellow and white varieties of 

 corn were grown in the pollinating 

 plat and were shedding pollen at the 

 same time, so that if much contamina- 

 tion had occiu'red some of it should 

 be apparent as xenia. Most of the 

 ears have now been shelled and very 

 few cases of contamination have been 

 observed. It seems likely, moreover, 

 that there is at least as little danger 

 of contamination in using this method 

 as there is in any method that in- 

 volves even the briefest exposure of 

 receptive silks to a pollen-filled atmos- 

 phere. 



The method can be utilized in cross 

 pollination when it is not necessary to 

 use the tassel more than once. It also 

 may be possible to use only individual 

 branches of a tassel so that several 

 pollinations can be made from a single 

 plant. This seems worth trying be- 

 cause of the safety of the method, in 

 spite of the fact that it does not lend 

 itself as well to the less routine opera- 

 tion of crossing. In self-pollination, 

 however, the method is not only safe 

 but efficient. 



