CYTOLOGY OF REFRODUCTION IN PLANTS 



159 



whole cycle except in the gametes. Meiosis occurs in the male and 

 female gametangia when the nuclei of the biciliate gametes are formed. 



Developing Conjugation Tube 



Conjugation Tube 



Male Gamete 



Male Gamete 



Female Gamete 



Female Gam£te 

 Zygote 



Fi(i. 117. — Stages in the union of gametes and the formation of the zygote in the green 

 alga Spirogyra. Explanation in text. {From Smith, Overton, et al.: A Textbook of General 

 Botany, Ath ed.. The Mactnillan Com^pany.) 



Fig. 1 

 in text. 

 Company. 



18 

 {Fro 



.) 



Stages in tlie history of a zygote of the green alga Spirogyra. Explanation 

 m Smith, Overton, et al.: A Textbook of General Botany, -Ith ed.. The Macmillnn 



Such gametic meiosis is very rare in plants. The female gamete contains 

 numerous plastids, while the male is much smaller and contains only one. 

 After syngamic union the resulting zygote develops at once into a new 



