ZOOSPERMS OR ANTHEROZOIDS. 



Ir- 



in agreement with this, Strasburger has for several years past laid particular 

 stress on the fact that in the Phanerogams the two cell-nuclei which were already 

 present in the pollen-grain pass forward into the growing-end of the pollen-tube, 

 and are carried with this into" the micropyle and then disappear, thus probably 



Fig. 447.— Antheridia of Adiaiitiim Capillits-Veneris (X 550) in optical 

 longitudinal section. / is still immature ! in // the antherozoids are already 

 formed ; /// has ruptured by the peripheral cells swelling radially, and the 

 antherozoids have nearly all escaped. / prothallium ; a antheridiuni ; b its 

 vesicle, containing starch-granules. 



Fig. 448.— Young Archegonia of Pteris ser- 

 <-u!ata (after Strasburger), e oosphere ; /; h 

 leck ; A'canal-Lcllb. 



Fig. 449.— Germination of microspores and development of antlierozoids of IsocUs laiiistiis (after Millardet). 

 .■/ and C microspores from the right side ; B and n from the ventral side. A and ß show the development of 

 the antheridium. SS dorsal cells ; ß ß ventral cells. C and Z) show the development of the antherozoids. 6 and /3 have 

 disappeared, v in A—D is the vegetative cell (Millardet's prothallium). a—/ development of the antherozoids. 

 (,A—D, a and d X 580, e andy X 700.) 



becoming dissolved, and, hypothetically at least, we may assume that here also it 

 may be the nuclcin which is passed over to the oosphere in a state of solution 

 by the agency of the synergidce. In cases where numerous pollen-tubes are 

 develo})ed from one pollen-grain, the nuclear substance is, according to Strasburger, 

 previously dissolved in the protoplasm, apparently in order to distribute itself 



3 1^ 2 



