154 ORGANOGUAPHY. BOOK I. 



of which sepai'ated from the mass, which proved that a force 

 of some kind held them together. Shortly after four append- 

 ages, like knife blades, developed at equal distances on the 

 inner face of the pollen cell, and gradually directed their edge 

 towards the centre, so that they began by cleaving the granu- 

 lar mass in four different lines, and finished by dividing it 

 into four little triangular masses ; and when the appendages 

 met in the centre they grew together, and divided the cavity 

 of the pollen cell into four distinct cavities, which soon 

 after rounded oif their angles, and in a short time the little 

 granular masses became spherical, like melted lead run into 

 the hollow of a bullet-mould. The partition of the mass thus 

 brought about by the appendages seems to me to indicate that at 

 this period the mass was not protected by a special integument, 

 and that the mutual adhesion of the granules was very weak. 



" When things had arrived at this point, the portion of the 

 tissue formed by the pollen cells separated itself from the 

 surrounding parts, and each pollen cell became loose, gene- 

 rally in the form of a square parallelopiped with rounded 

 angles; each little mass of granules gained a smooth, colourless, 

 transparent membrane, which was at first membranous but 

 afterwards became thick and succulent, and soon began to 

 take on the characters peculiar to the pollen of the gourd. 

 The integument began to bristle with fine conical papillae ; 

 several roundish lids were traced out here and there on its 

 surface ; it hardened, became opaque, assumed a yellow colour, 

 ceased to grow, and attained its perfect maturity." Mirbel 

 adds to this highly interesting statement, that he finds in the 

 generality of plants that the mode of forming the pollen is 

 much the same as in the Gourd. 



The granules of pollen are commonly distinct from each 

 other. They are, nevertheless, in certain cases, found in 

 various states of cohesion. In some plants they cohere in 

 threes or fours, as in many Orchideae ; or in clusters of many 

 grains, as in Acacia (Plate IV^ fig. 28.). In some, as the 

 Fuchsia, CEnothera, &c., they hang together by a sort of 

 cobweb substance, which is the remains of the cellular matter 

 in which they were engendered. In other cases they coalesce 

 in masses, having a waxy textvire and colour, and occupying 



