170 



EDWARD C. JEFFREY ON 



complete series of embryos of E. arvense and E. limosum to describe completely the embry- 

 ogeny of these species. Moreover, the examination of the earlier phases of development 

 is rather to be passed over in this essay since a good deal of attention will he given to 

 the later stages which have been almost entirely neglected by previous writers. 



The first shoot of E. hiemale, after bursting through the calyptra, forms from six to 

 twelve segments, and then ceases to grow. Some time previously, however, the first so- 

 called adventitious shoot has emerged below the point of attachment of the first foliar 

 whorl of the primary axis. This secondary axis is terminated interiorly by a root which 

 originates below its primary whorl of leaves or ochreola. The secondary axis is followed 

 by a tertiary axis which springs from below its first sheath and between two leaf-traces. 

 These features are represented in PI. 26, figs. 1), 10. The next figure shows us a some- 

 what older plant, in which a number of shoots have been successively formed in the order 

 indicated by their numeration. It is to be observed that each shoot has a corresponding 

 root. In the. stouter later shoots the nodal buds, which develop normally as shoots, are no 

 longer confined to the basal nodes, but appear also in relation to the higher articulations, as 

 may be learned from PI. 26, figs. 10, 11. As each new axis originates well down towards 

 the attachment of the root of its predecessor, the later formed shoots are continually more 

 deeply buried in the soil, Fig. 11. In E. hiemale twelve or more erect shoots are formed 

 before a horizontal rhizome makes its appearance, from the base of. one of the larger and 

 more deeply buried secondary upright axes. It would be interesting to discover if the 

 depth of the parent axis in the soil has anything to do with the formation of these 

 plagiotropic shoots ; the writer, however, has not made any experiments in this direction. 

 The first shoot of hiemale has foliar sheaths of three members, the second shoot has 

 frequently similar sheaths, but more often has whorls of four united leaves, then follow 

 axes with verticils of four, five, and six members. 



The writer's cultures of E. limosum did not produce plants of more than two devel- 

 oped shoots. It is apparently difficult to secure the proper conditions for the continued 

 growth of this species, for, unlike E. hiemale, it does not live long under greenhouse 

 conditions. Here the first shoot may have leaf-whorls of only two members ; in fact, the 

 plants grown from spores obtained from a swamp about fifty miles northeast of Toronto, 

 were practically all characterized by this peculiarity. Buchtien (&p. cit., p. 40) has 

 noticed a similar peculiarity in the case of E. variegatum. Sporophytes from spores 

 gathered by the writer from plants on the border of HoAvard Lake in High Park, Toronto, 

 had, on the other hand, almost invariably sheaths of three members. A study of the 

 sporogeny showed that in the former case a considerable number of spore-mothers became 

 disintegrated after the tetrad division had taken place. This did not occur in the material 

 from High Park. It is possible that, in the first instance, too large an amount of spo- 



