46 



THE BOTANICAL MAGAZINE. 



[Vol. XXII. No. 2.'54. 



enlarges more rapidly and becomes surrounded by a denser 

 mass of cj'toplasm and forms the so-called body-cell, and the 

 other, the stalk-nucleus, remains comparatively' small in size 



and lies free in the 

 c^'toplasm of the 

 tube. The exact 

 moment of the 

 division has not 

 been determined, 

 but it seems pro- 

 bable that it takes 

 place very soon 

 after the entering 

 of the generative 

 nucleus into the 

 tube. As the pollen- 

 tube grows down- 

 wards the bod\--cell 

 and two nuclei in- 

 crease in size, the 

 latter being usually 

 found ahead of the 

 former (Fig. 2). 



About the end 

 of June the pollen- 

 tube reaches the 

 female prothallium 

 and soon penetrates into the depression just above the arche- 

 gonial complex. The body cell which is almost spherical and 

 contains one large nucleus with a prominent nucleolus, now lies 

 at the enlarged tip of the pollen-tube (Fig. 8). The tube- and 

 stalk-nucleus, which are found just below the body-cell, being 

 imbedded in a mass of starch-granules (Fig. 3). The body-cell 

 then divides to form two sperm-cells. The division takes place 

 during the first few days of July. The sperm-cell contains 

 numerous starch- granules, and is ready to fertilize soon after 

 its formations (Fig. 4). 



Fig. 1. Pollen-grain just before pollination. — Fig. 2. 

 Pollen-tube with the bodj-cell, stalk- and tube-nucleus. 

 — ^Fig. 3. Body-cell with two nuclei, as they are situated 

 at the tip of the pollen-tube. — Fig. 4. Two sperm-cells. 

 X435. 



