VOLUME LIV 



NUMBER 2 



THE 



Botanical Gazette 



AUGUST 19 1 2 



SPERMATOGENESIS IN EQUISETUM 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 1 58 



Lester W. Sharp 



(WITH PLATES VII AND VIIl) 



Historical resume 



The cilia-bearing organs of the motile cells of plants have formed 

 the basis of a number of researches during recent years. In the 

 majority of cases in which the bearing of the results has been given 



consideration, the discussion has centered about the morphological 

 nature of these organs, and in this discussion a very prominent 

 place has been taken by the centrosome. 



Among the earliest investigations in this field were those of 

 Strasburger (78) on the algae. During the development of the 

 ' swarm spores of Oedogonium, Cladophora, and Vaucheria he found 

 that the nucleus approaches the plasma membrane, which at that 

 point becomes thickened, forming a lens-shaped Mutidstclle. 

 From this grow out the cilia, and at the base of each a small refract- 

 ive granule is present. A full discussion of the morphological 

 nature of these cilia-bearing structures and an extensive comparison 

 with those of higher plants were given in connection with a later 

 Work (80). The main point to be noted at this time is that Stras- 

 burger believed that the blepharoplasts of higher plants have been 

 derived from such swollen Uautschicht organs in the algae, and that 

 all of them are morphologically distinct from centrosomes. 



Daxgeard (17) found a deeply staining granule at the base of 

 the cilia in Chlorogoniunu but did not consider it a centrosome. In 



89 



