66 
F. IV. Oliver. 
then the observation has a certain, if unimportant, bearing upon 
current views regarding the phytogeny of the Cycadales. Scott’ 
in his interesting discussion of the Botryopterideae correlates the 
French and English representatives of the group and shows how 
they are to be regarded as representing the more simply organised 
stock of the primitive Ferns, the polystelic Marattiaceae being the 
more complex. On purely anatomical grounds the Botryopterideae 
seem to have a claim to affinity with the stock from which the 
Cycadofilices arose, and in our present lack of knowledge concerning 
the manner of fructification of this group, the suggestion that the 
vascularity now found in the sporangium of an apparent Botryop- 
teridea may be homologous with the tracheal tissue which we 
recognise as so characteristic and well marked a feature in the early 
Gymnosperms does not appear wholly unreasonable. Whilst in our 
sporangium, and in the Botryopterideae generally perhaps, if my 
surmise be well founded, the tracheal sheath served the simple end 
of conveying water to the ripening spores (perhaps under xerophilous 
conditions), in the early Gymnosperms it has undergone a marked 
advance and specialisation, in harmony with the modified fate and 
enlarged functions of the macrosporangium; and at the same time 
has come to discharge functions more complex than the mere 
supply of water to a sporogenous tissue. 
University College, London. Jan., 1902. 
1 Loc. cit., pp. 277 and 507. 
EXPLANATION OF THE PHOTOGRAPHS* AND FIGURES ON 
PLATE I. 
Illustrating F. W. Oi.ivKk’S paper on “A Vascular .Sporangium.” 
PLATE I. 
Photograph I.—Transverse section of the sporangium (x no). 
t 1 solitary tracheal elements. 
t 3 and t G groups of three and six tracheal elements. 
Photograph 2.—View of the tracheal group t G (of photo. 1) under 
higher magnification ( x 290). 
t-t tracheal elements (six in all). 
g gap in wall. 
Photograph 3.—View of the tracheal group l 3 (of photo. 1) under 
higher magnification ( x 290). 
w thick part of sporangial wall. 
t tracheal group. 
*1 am indebted to Mr. W. Tams, of Cambridge, for the trouble he has 
taken in obtaining the photographs reproduced here. 
