246 HORTICULTURAL SOCIETY OF NEW YORK. 



them stick to one another more or less so that the pollen, whether it lies dry 

 on the slide or is placed in liquid media, arranges itself in a succession of 

 clumps. This mucilaginous substance does not appear to be soluble in water 

 as the pollen grains retain their position even after several days in the solu- 

 tions. The self-sterile pollen, on the other hand, shows no such arrangement, 

 but the grains distribute themselves either on the slide or in the liquid like so 

 much dry powder, quite by chance. 



The next phase of the work was the microscopical examination of the 

 pollen grains to see if there were any characteristic differences in the size 

 or shape of the different classes of pollen. All pollen, whatever its shape 

 may be when it comes from the anther, swells on contact with water and 

 most other liquids, assuming a spherical shape. The results of this part of 

 the work can be better illustrated than told. On the following pages are cuts 

 which are reproduced from photo-micrographs of the pollen mounted in bal- 

 sam. The characteristic differences are very apparent. The self-fertile forms 

 are oblong, blunt at the ends and quite symmetrical. The self-sterile sorts 

 as may be seen are quite different in shape, being more irregular and showing 

 little of the symmetry of the other class. Pollen from all other varieties in 

 the list previously given showed these same shapes according to the class 

 to which the variety in question belonged, but the blooming season of the 

 first eight varieties was past before I thought of illustrating this phase of 

 the work, and later the balsam mounts of Roscoe and Lindmar were acci- 

 dentally destroyed. 



Examination of pollen, from varieties of grapes which had given conflict- 

 ing results in Prof. Beach's work to determine if they were self-sterile, 

 showed that these forms may be mixed. Eaton was the first one of these 

 which was examined on June 26. The pollen of this variety is quite irregular 

 in shape and size, and only about 10 per cent, show the regular self-fertile 

 shape, although there are numerous others which approach it very closely. 

 They are considerably larger than average pollen. In 20 per cent, sugar 

 solution about 15 per cent, of this pollen germinated. None of the growths 

 appeared healthy, however, or at least were not like those of completely self- 

 fertile pollen. In normal self-fertile pollen the tubes formed on germination 

 are approximately the same size throughout, but the tubes of Eaton varied 

 in size at different points of their course, being restricted at one place and 

 swollen and distorted at another. The tubes were fully as long as those 

 of normal self-fertile pollen. Other pollen of the same class which Prof. 

 Beach brought for testing were Dracut, Amber, Maxatawney, Faith, Geneva, 

 Montefiore, Caronicus, Oneida, Gold Dust and White Jewel. These were 

 tested, as were also pollen of Red Trattmener, Red Veltliner and Chables 

 sent by Dr. Tinker, of New Philadelphia, Ohio. In each instance the per- 

 centage of pollen which germinated did not vary widely from the percentage 

 of self-fertile forms which the microscope showed that particular variety to 

 contain. And it appears very certain that the capacity of the pollen for 

 growth is in direct proportion to the percentage of self-fertile forms present 

 and their conformity to the self-fertile type. Pollen of various varieties of 



