no 



A TEXT-BOOK OF BOTAXY. 



we have also to note the character of the male gamete or sperm. 

 With the exception of the Cycads and Ginkgo, motile sperms are 



Fig. 71. Development of gametophyte and embryo in one of the Coniferae. e, em- 

 bryo-sac (megaspore); a, archegonium; h, neck of archegonium; i, integument; p, pollen 

 tube; n, nucellus; f, wing of seed; g, fibrovascular tissue; kz, canal cells of archegonium; 

 ka, beginning of embryo; k, nuclei; ws, tip of root; wh, root-cap; c, cotyledons; v, point of 

 growth of stem; s, suspensor. 



I, early stages of embryo-sac (e); II, young archegonium (a) after development of 

 neck cells (h), cell lumen (1); III, section of ovule with portion of attached seminiferous 

 scale (f) showing entrance of pollen tube; IV, embryo-sac with two developed archegonia; 

 V, archegonium after fertilization, there being four nuclei at the lower part, only two of 

 which are seen; VI, further development of embryo; VII, VIII, IX, X, showing develop- 

 ment of large tortuous suspensor, to which is attached the young embryo (ka) ; XI, XII, 

 mature embryo, — After Strasburger. 



