the Anatomy of the Cone and Fertile Stem of Equisetum. 449 
actually continuous with the partially disorganized tracheides projecting 
into the latter. Moreover, in some specimens of the species in question 
continuity of metaxylem and protoxylem may be observed before the 
destruction of the latter is completed. 
* Although such species as E. arvense and E. maximum show a 
definite network of strands with short meshes, in E. palustre, E. limosum , 
E. sylvaticum , the meshes are more irregular— frequently much elongated — 
stretching for two or more “ nodes ”, and in E . palustre even extending the 
whole length of the cone ’ (Barratt, p. 226). 
As regards this second quotation I find myself unable to agree to the 
inclusion of E. maximum among the species, the stele of the cone of which 
shows a definite network of short meshes. An examination of Pis. XII and 
XIII of my paper dealing with the cone of this species will show that 
the stele possesses a very irregular network of meshes, many of which 
are long. This is true especially of the larger of the two cones, in which 
one of the meshes is of the seventh order, and twelve others are of the 
eighth or higher orders (Browne (2), Pis. XII and XIII). The only 
reconstruction of part of the network of the cone of E. maximum published 
by Barratt contains too few meshes to afford a reliable basis for generaliza- 
tion. Only thirteen meshes or portions of meshes of any considerable extent 
are shown ; of these, however, only five are of the first order, while two are 
entering unclosed upon a fourth internode. Again, though in the cones of 
E. palustre the meshes are, on an average, much longer than those of 
E. arvense , they can hardly be said to extend nearly the whole length of the 
cone, at any rate on the evidence published, though of course this may be so 
in specimens with a reduced vascular system. 1 Such a description would, 
however, apply to certain of the meshes of the cones of E. limosum . 
After concluding that the existing structure in vegetative and repro- 
ductive axes has been derived from a siphonostele, Barratt proceeds to 
deal with the problem of the determining factor associated with the distribu- 
tion of the parenchymatous tracts. Of this question she writes : ‘ Can 
it be met by an application of the conception of foliar gaps which is 
associated with the study of filicinean anatomy ? Browne 2 has attempted 
such an explanation in her papers dealing with the cones of several species 
of Equisetum . She homologizes the parenchymatous meshes with foliar 
gaps, associating them with sporangiophores, and considers that these 
organs are modified®whole foliar structures. . . . 
‘ Even if the sporangiophores were foliar structures, the anatomy does 
not favour the view that the meshes are foliar gaps. Jeffrey has pointed 
1 In the case of the reconstruction published by me (Browne (1), Text-fig. 4 ) of the stele of the 
variety polystachion of E. palustre the meshes may be said to extend nearly the whole length of the 
cone. This is, however, not due to their height, but to the reduction of the whorls of these cones, 
borne on lateral branches, to four. 
2 i. e. the present writer. , 
