126 peesident's addeess. 



variecorum ; or the grains themselves are sticky, either from an 

 uniform secretion or from local drops, thus Ahutilon venosum 

 has tiny drops, Eujihorhia splendens gelatinous ovals, Wistaria 

 Chinensis clinging masses. Most pollen is more or less soft, but 

 that of some Orchids is not only dry and hard, but brittle like 

 resin, as that of Calanthe lutea. 



Geouping of Pollen. Pollen is either simple or compound, 

 usually simple. As a rule the compound are groups of four 

 grains, or multiples of four. Occasionally one grain of a group 

 may remain rudimentary, hence threes, sevens, etc., are met 

 with. Such must be looked upon as exceptions. 



Groups of pollen are the grains of one or more mother-cells. 

 Though groups of four may be taken as normal, in the Acacias 

 the sub-division is carried far beyond, to eight, twelve, sixteen, 

 thirty-two, and even sixty-four ; and probably often in such 

 polygonal pollen as that which is characteristic of the Caryo- 

 phylacecB, as Stellaria and Dianthus Indeed any part, or even 

 the whole contents of an anther-sac may remain united in one 

 mass, pollinia, as in Orchis maculata. The Orchids, in fact, 

 present every phase, from separate grains, to pollinia ; thus, 

 separate grains, C'ypripedium ; four-fold groups (mother-cells), 

 Neottia ; all the pollen of a primary mother-cell, Ophrydce ; all 

 the grains of one pollen-sac and even of an anther head, Onci- 

 dium, Hahenaria, and Dendrobium Similarly the sporangia of 

 ferns exhibit often masses of spores, as Adianium capillis-veneris 

 and Davallia pyxidata. 



Not unfrequently pollen grains from the same anther appear 

 of two sizes, as in Spinacea oleracea, the larger being about six- 

 . teen times the bulk of the smaller. The smaller are single cells, 

 the larger are mother-cells. Potentilla anserina also shows two 

 sizes, the larger being groups of four, just as Symphytum 

 officinale has often double grains. The Crocus and Scabious 

 similarly present two sets occasionally. 



A few examples of the various modes of division by which 

 groups are formed may perhaps prove acceptable. Melampyrum 

 sylvaticum shows longitudinal division into two, splendidly, as 

 Bunium Jlexuosum and Pulmnnaria officinalis do by transverse 



