THE MAN'S HOUSE. 121 



B) , so that it resembles a honeycomb. (4) Valvular ; here the sutures 

 remain closed, and the face of the anther is cut into portions which 

 lift like a hinged trap-door or valve (L. valva, folding-door). This 

 mode characterizes the Laurel Family (Fig. 170, 6). 



268. Pollinia are pollen-grains generated — as all pollen-grains are — 

 in mother-cells which persist, instead of being obliterated (as is usual) ; 

 and thus the grains are retained in masses. 



269. In the Orchids (Fig. 171) the pollinium often lengthens into a 

 stalk, called a Caudide (L. little tail) ; the caudicle is attached to a 

 viscid disk, called Retinaculum (L. stay). This stay lies loosely in a 

 cup-shaped, beaked body, called a Rostellum (L. beak). The rostel- 

 lura is an abortive stigma transformed. In the Milkweed (Fig. 1 72, 

 D) each pollinium is provided with a tail, called a. Queue; the two 

 queues are attached to a common gland, and when ready for fertiliza- 

 tion, this gland adheres closely to the stigma, whilst the pollinia open 

 and discharge their grains upon it. 



270. Formation of Pollen. — The anther develops before the filament, 

 and is therefore always sessile at first, appearing as a small swelling 

 composed of similar cells. Presently some of these cells destroj' them- 

 selves, as it were, — they change into lacimes, or empty spaces ; these 

 are at first small and linear; then they enlarge, become oblong, and 

 are usually four in number, two for each anther-lobe. Soon they are 

 filled with a mucilaginous fluid, which forms cells (Fig. 173, A) ; the 

 outermost of these cells become the fibrous envelope of the anther ; the 

 inner cells, which are much larger, are the Pollinie Utricles, or Pollen- 

 Mothers. Each pollen-mother forms four cells ; each cell (Fig. 173, 

 B) forms a pollen-grain. The pollen-mothers are usually obliterated, 

 as has been said, after the grains ripen ; but in the Orchis and Milk- 

 weed they persist. 



271. Pollen-grains arc as varied as flowers ; their adornment is more 

 wonderful than that of the flower. The pollen-grains of the Squash 

 and Passion-flower are elegantly chased and sculptured. Those of the 

 Pines (Fig. 4, g) are triangular; the extine swells on either side into 

 two little balloons, evidently contrived to assist in transporting the 

 pollen, which is borne by the wind to the female flower. Those of the 

 Hollyhock are round (Fig. 4, s) and bristling with pointed prickles. 

 Those of the Milkwort (Fig. 4, 2) have longitudinal furrows. Those 

 of the Cherry are round; of the Evening Primrose triangular (Fig. 

 4, 3,4). Most of these forms and carvings are designed to attach the 

 grains to the proboscides of insects, or to the feet, which are also pollen- 

 bearers. The pollen-grains of the Zostera, or Sea-wrack (which is a 

 marine plant), have but one coat, the inline; they are exquisitely 

 slender and delicate, lying side by side, like skein's of silk, in the 

 anther-lobe. The Fovilla, or nourishing fluid, in the pollen-grain we 

 remember in Lesson II. (19). 



11 



