THE (i KNITS KQUISETIJAF. 



107 



require special description, as they have been fully investigated in recent years by Buch- 

 tien and Belajeff. 



The archegonia, however, require'more attention. They originate, as has been 

 observed by other writers, frequently, but not invariably, near the base of a prothallial 

 lobe. A superficial cell becomes more rich in protoplasm than its neighbors, and under- 

 goes transverse division into nearly equal parts, in this respect presenting a contrast to 

 the mother-cell of the archegoniura of the isosporous Filicales, where the first division 

 results in the formation of a shallow outer cell and a much deeper inner one, PI. 26, 

 fig. 1. The young archegonium in the two-celled stage resembles closely that of 

 Lycojjodmiu davatum (Brnchmann, U. d. prothal. u. d. keimpflanzen mehrer. europ. 

 Lycopod., PL 3, fig. 12; I am indebted to Dr. G. L. Goodale for calling my attention to 

 this recent work) of the same age. Treub (Annales du jardin bot. de Buitenzorg, torn. 4, 

 5) unfortunately does not figure such early phases in the case of L. cernaum and L. 

 phlegmaria. In PI. 20, fig. 2, is represented a later stage, in which the inner cell has 

 become equally divided by a second transverse wall. The outer cell at nearly the same 

 time becomes bisected by a perpendicular wall. Frequently the outer cell at this time is 

 still undivided, and in such cases the perpendicular row resembles the three cells of the 

 young archegonium of the isosporous Filicales, but the significance of the cells in the two 

 cases is very different, in the former they are cervical cell, cervical canal-cell and central 

 cell; in the latter, cervical cell, central cell, and basal cell. It was probably an 

 archegonium at this stage of development somewhat obliquely cut and consequently 

 showing only part of the central cell, which led Campbell (Delt. of mosses and ferns, 

 p. 430, fig. 223b) to make the statement that a basal cell sometimes occurs in the 

 Equisetaceae. 



Janczewski (Bot. zeit, 1872, p. 420) , Sadebeek (Schenck, Handbuch d. hot., bd. 1, p. 

 196), and Buchtien (op. tit., p. 25), all agree in stating that there is no basal cell in the 

 archegonium of the genus Equisetum, and with this assertion my own observations on a 

 large number of examples of E. hiemale, E. limosum, and E. arvense are quite in accord. 

 PI. 26, fig. 3, represents a young archegonium of E. hiemale, in which the central cell has 

 already given off the ventral canal-cell, and as a result has become the egg-cell. The neck 

 has become further developed and the cervical canal-cell is beginning to push its way up- 

 wards. In PI. 26, fig. 4 is represented a nearly ripe archegonium. The neck remains 

 short in E. hiemale. The cervical canal-cell has become longitudinally divided into two, a 

 peculiarity which has only been described elsewhere in Lywpodium phlegmaria (Treub, 

 Ann. du jardin bot. Buitenzorg, torn. 5, pi. 21, figs. 9 and 10). The ventral canal-cell has 

 already begun to degenerate. Around the egg-cell cells are cut off from the prothallial 

 cells, by walls parallel to its surface, a feature first observed by Hofmeister and confirmed 



