88 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
on several seaweeds caused by animals; the Chytridiaceee which inhabit 
freshwater and marine algae ; the algal parasites Chlorochytrium and 
Phyllo siphon ; and the bacteria which cause tubercles on the fronds of 
Florideae. 
Mr. A. H. Church * records the frequent occurrence of a pyrenomy- 
cetous fungus on the swollen fertile pods of Ascophyllum nodosum. 
B. CRYPTOGAMIA, 
Cryptogamia Vascularia. 
Siliceous Deposit in Selaginella.j — Mr. E. J. Harvey Gibson has 
examined the siliceous deposit in the cortex of a large number of species 
of Selaginella. He thinks it probable that the silica is an excreted 
product, and that calcium and magnesium are absorbed, at least in great 
part, in the form of soluble silicates, the silica being then eliminated in 
the soluble form. 
Sporophyte of Equisetineae and Lycopodineae.J — Prof. F. 0. Bower 
discusses several theoretical points respecting the general morphology 
of the sporophyte of the Archegoniatse, and the modes in which plants 
with numerous separate archespores may have originated from plants of 
the bryophytic type. There is no definite position for the archespore 
which applies to all Vascular Cryptogams. The author argues that 
there is no essential difference between the tissue which will form septa 
or trabecules and that which will form spores, since they can mutually 
undergo conversion. 
Development of Marattia.§ — Prof. D. H. Campbell has investigated 
the development of Marattia Bouglasii, and considers that his observa- 
tions confirm the view that the eusporangiate ferns are primitive forms, 
and show that Marattia is the nearest form to the Hepaticae yet ex- 
amined, especially approaching the Anthocerotem. The antherids most 
nearly resemble in structure those of Equisetum. The archegones are 
on the under side of the protliallium ; and the embryo, in its develop- 
ment, retains its direct upward growth, and bursts through the pro- 
thallium, which remains surrounding the base of the young plant, and 
continues to supply nutriment to the sporophyte after the latter becomes 
independent. 
Structure of Lepidostrobus.|| — From a careful examination of Lepi- 
dostrobus Brownii Prof. F. 0. Bower concludes that the synange of the 
Psilotaceae is homologous with the sporange of other Lycopods ; that 
the sporangiophore is a branched leaf homologous with the simple 
sporophyll of Lycopodium or Lepidostrobus ; and that the single fruiting 
axis of Tmesipteris or Psilotum is comparable to a lax lycopodinous 
strobilus. The lacunar structure which is so frequent in cortical tissues 
of various fossil lycopodinous plants he regards as attaining a specialized 
development in the trabeculae of Selaginella . 
* Ann. Bot., vii. (1893) pp. 399-400. f Tom. cit., pp. 355-66 (1 pi.). 
t Proc. Roy. Soc., liv. (1893) pp. 172-6. Cf. this Journal, 1893, p. 761. 
§ Bot. Gazette, xviii. (1893) p. 337. 
j| Ann. Bot., vii. (1893) pp. 329-54 (2 pis.). 
