April, 1907.] Development of Sporangium of Equisetum. 
125 
Later stages of the sporangium are similar to what Bower 
found for E. limosum and E. arevense. A large number of 
sporocvtes are developed, about forty in radial section, many of 
which become disintegrated during the formation of tetrads. 
The most striking difference is in the first stage of the spor¬ 
angium. The large cell (Fig. 1) which cuts off the first cell of 
the sporangium is very sharply differentiated from its fellows by 
the size and structure of its nucleus and by the way its cytoplasm 
stains. The lower cell and its descendants are distinctly dif¬ 
ferentiated from the rest of the tissue through several stages of 
the sporangium. The outer half of the large cell, the first cell of 
the sporangium, always divides anticlinally which is contrarv to 
the usual method of division of the sporangial initial in the 
Equisetales. Taking these facts into consideration together 
with the position of this large cell, the conclusion is reached that 
it is homologous with the sporangial initial figured by Bower for 
E. arevense and that in E. hyemale the sporogenous tissue comes 
•entirely from the primary wall cell while the inner cell is sterile. 
Summary and Conclusion. 
1. Equisetum hyemale is the of eusporangiate tvpe. 
2. The sporogenous tissue comes from a single cell. 
3. The first wall is perielinal the inner cell being sterile, 
while the sporogenous tissue comes entirely from the outer cell. 
4. The tapetum comes from the cells surrounding the 
sporogenous mass. 
5. There are two types of sporangia differing in develop¬ 
ment and governed by the direction of the second division. 
0. Many of the sporocvtes are disintegrated during the 
formation of tetrads. 
Bibliography. 
1. Goebel, K. “ Beitrage zur vergleichenden Entwickel- 
ungsgeschichte der Sporangien.” Bot. Zeit. 38:545. 
2. Bower, F. O. “Studies in the morphologv of spore 
producing members. Equisetineas and Lycopodineae,” Rov. 
Soc. Phil. Trans. 1894, page 473. 
3. Campbell, D. H. “Structure and Development of 
Mosses and Ferns,” page 475. 
EXPLANATION OF PLATES. 
All figures were made with a Bausch and Lomb camera 
lucida and a Bausch and Lomb 1-12 oil immersion 1.32 N. a. 
objective with Leitz No. 4 ocular was used for all but Fig. 19 
where a Leitz 1-7 objective with a No. 2 ocular was substituted. 
The original magnification was approximately 1500 diameters 
for all but Fig. 19 which was about 670 diameters. Drawings 
were reduced to one-fourth diameter of original magnification. 
