98 DESCRIPTIVE BOTANY. PAK1 I. 



coats, and are generally spherical or spheroidal, and 

 often have determinate markings, warty projections, and 



minute bristles upon their surface. Some of the larp-M 

 grains do not exceed the 7 | c or -^ part of an inch 

 in diameter ; and in some species they are not so much 

 as the TV i, 1 ,,,,. In several species, the grains approach 

 a tetrahedral shape ; others are very singularly modi- 

 fied, of which the few examples represented in the an- 

 nexed cut may serve as a specimen. In some tribes 

 of the remarkable order Orchideac, the grains ad- 

 here together in waxy " masses," which fill the anthers. 

 Each grain of pollen contains a quantity of minute 

 " granules," the largest of which do not exceed the 

 i~To?TU P art f an inch- These are occasionally inter- 

 spersed with oblong particles, two or three times larger 

 than the granules. We reserve further details for the 

 physiological department, when we shall speak of the 

 manner in which the grains act upon the stigma, in se- 

 curing the fertility of the ovule. 



(100.) Pistil. The parts which compose the in- 

 nermost whorl or whorls, are termed carpels, as we have 

 already stated (art. 92.) ; and when they are not united 

 together, each is also considered as a " pistil." This 

 pistil, whether simple or compound, consists essentially 

 of an " ovarium" or " germen," containing the young 

 seed or " ovules ; " and of a " stigma," or glandular 

 summit, which is either seated immediately upon the 

 ovarium, or on a sort of stalk, called the " style,' 



