ZOOSPERMS ORTANTHEROZOIDS. 



771 



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 



/? A 



Fig. 447. — Antheridia of Adiantnm CapilluS'Veneris (x SSo) 'n optical 

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

 fonned: /// has ruptured by the peripheral cells swelling radially, and the 

 antherozoids have nearly all escaped, p prothallium ; a antheridium ; b its 

 vesicle, containing starch-granules. 



FIG. 448.— Young Archegonia of PUris ser- 

 rtilata (after Strasburger). e oosphere ; h h 

 neck; A' canal-cells. 



Fig. 449.— Gennination of microspores and development of antherozoids of Iso'e'tes laciistris (after Millardet). 

 A and C microspores from the right side ; B and D from the ventral side. A and B show the development of 

 the aotheridiuin. 5fi dorsal cells ; ^ ^ ventral cells. C and D show the development of the antherozoids. d and i3 have 

 disappeared, -o in A~D is the vegetative cell (Millardefs prothallium). a—f development of the antherozoids. 

 (A-~D, a and d X 380, e andy x 700.) 



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

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

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

 developed from one pollen-grain, the nuclear substance is, according to Strasburger, 

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



3 D 2 



