THE GENUS EQUISETUM. 167 



require special description, as they have heen fully investigated iu recent years by Buch- 

 tien and Belajeft". 



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 archegoniam 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 archegoniiim in the two-celled stage resembles closely that of 

 Lyco2wdmm davatum (Bruchmann, U. d. prothal. u: d. keimpflanzen mehrer. europ. 

 Lycopod., PI. 3, fig. 12; I am indebted to Dr. (J. L. Goodale for calling my attention to 

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

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

 jMec/maria. 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 i\i 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 

 ca?es is very different, in the former they are cervical cell, cervical canal-cell and central 

 cell; ill the latter, cervical cell, central cell, and basal cell. It was probal)ly an 

 archegouimn 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. 



.lanczewski (Bot. zeit., 1872, p. 420), Sadebeck (Schenck, Ilandbuch d. Ijot., bd. 1, p. 

 100), and Buchtien [o^). cit., p. 20), all agree in stating that there is no basal cell in tlie 

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

 large number of examples of J'J. JiiemaJe, E. Ihiiosrua, and E. (irpenae are ([uite in accoi'd. 

 PI. 26, fig. 3, represents a young archegonium of E. hlemde, 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 [lush its way iqi- 

 wards. In PI. 20, fig. 4 is represented a nearly ripe archegonium. The neck remains 

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

 peculiarity which has only been described elsewhere in Lycopodlnin phlcymdrUi (Treub, 

 Ann. du jardin bot. Buitenzorg, tom. 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 



