Review). 
i 26 
of production of the reproductive cells. A conception of this kind 
would seem amply to cover the facts cited by Professor Bower, 
without any appeal to a definite evolutionary sterilisation of obligate 
sporophylls. 
In a chapter on Embryology and the Theory of Recapitulation 
Professor Bower reviews the history of this subject and shows how 
largely we have been obliged to abandon the somewhat rigid ideas 
of the earlier plant-embryologists. Out of the wreck, the author 
has saved the general fact of the origin of the stem-axis near the 
point of intersection of the octant walls of the epibasal hemisphere 
of the Pteridophytic embryo, and this he considers a material fact 
in relation to the strobiloid theory, because that theory “contem¬ 
plates the phyletic pre-existence of the axis.” With the author’s 
conclusions as to the secondary character of so-called “independent” 
roots and leaves and as to the true foliar nature of the “ cotyledon ” 
in Pteridophytes we are in close agreement. 
The author next presses the Stelar Theory into the service of 
his hypothesis of the strobilus. He argues that “ the existence of a 
cauline stele bears directly towards a strobiloid theory of the shoot,” 
and brings in the example of the vascular cylinder of the Moss 
gametophyte as an instance of the existence of a stele independent 
of leaf-traces, connecting this with the state of things existing in 
the microphyllous Pteridophytes. We may all agree that the 
anatomical structure of Pteridophytes lends no support to a phytonic 
theory, and that it is consistent , so far as the microphyllous forms 
are concerned, with the strobiloid theory. But it is just as 
consistent with the theory of origin of the sporophyte from a 
branching thallus. And when Professor Bower asserts, as he does 
in one of his headlines (p. 199) that the anatomical evidence “ shows 
microphylly to be primitive ” we must take leave to differ from him 
completely. The argument here is based on an apparent confusion, 
already alluded to, of a condition of protostely with cladosiphonic 
siphonostely. Mr. Gwynne-Vaughan will probably be surprised to 
learn that he has shown a “ transition from the cladosiphonic to 
the phyllosiphonic ” state in the young plant of Alsopliila excelsa. 
What really exists, of course, is a transition from protostely to 
siphonostely, and protostely is not a monopoly of the microphyllous 
forms, but is found equally among the primitive ferns. 
In dealing with the problem of symmetry in the sporophyte, 
the author seeks to show that “ the radial type of symmetry is the 
prior condition for the sporophyte at large ” (p. 203). No one could 
dispute this in relation to the Bryophytic sporogonium, though we 
cannot concede that any presumption as to the Vascular plants is 
involved in such an admission. At the same time we must frankly 
grant that we are impressed with the trend of the facts collected by 
Professor Bower to support the conclusion that the primitive 
symmetry of the Pteridophytic sporophyte is also radial, even in the 
Ferns. Such a conclusion, while in no way militating against the 
origin of the Vascular plant from a branching thallus, is certainly 
pro tanto opposed to the theory of its origin from a dorsiventrally 
organised thallus. 
In discussing the interesting question of “ The establishment 
of a free-living Sporophyte ” (Chap. XVII.) the author assumes, in 
accordance with his general theory, that the sporophyte being 
evolved from a sporogonium was originally completely dependent 
