BOTANICAL GAZETTE 



[JANUARY 



Figs. 30-33. — Fig. 30, vertical section of a 

 young sporogonium within the calyptra, 

 X132; fig- 31, transverse section of an arche- 

 gonial receptacle, cutting obliquely through 

 three sporogonia within their involucres 

 which show the vertical opening; fig. 32, 

 section through the region of contact of foot 

 and thallus (/, foot; /, thallus; m, mucila- 

 ginous remains; s, starch), X667; fig. a, 

 sketch of archegonial receptacle indicating 

 the position of the sporogonia. 



by the rapid growth of the 

 tissue above (fig. 12). The 

 stages of development that 

 appear indicate the sequence 

 usually given. In 1897 

 Gayet (ii) claimed that he 

 had demonstrated in Mar- 

 chantia, Preissia, and other 

 Hepaticae, that division in 

 the cover cell by intersecting 

 quadrant walls does not take 

 place until a late period, and 

 that before it occurs repeated 

 segments are cut off its lower 

 face, which add to the length 

 of the neck. Figs. 24, 26, 

 and 27 leave no room for 

 doubt that in Aytonia a 

 quadrant division occurs 

 early in the cover cell, and 

 that the neck lengthens by 

 divisions lower down. The 

 neck cells divide simulta- 

 neously until 8 cells are 

 formed (fig. 27), showing 

 greater regularity than is 

 commonly reported. The egg 

 has a large nucleus but no 

 "receptive spot"; it fills the 

 cavity of the venter up to 

 the time that fertilization is 

 to take place; then the cells 

 forming the wall of the venter 

 divide rapidly, parallel to the 

 surface of the egg; at the 

 same time there is an increase 

 in the size of the cavity or 



