354 BOTANICAL GAZETTE [May 
taurea, though he has not approached nearer a final explanation of the phenom- 
enon than others before him. A cross-section of the filament shows a dorsal 
region of collenchyma-like tissue with almost imperceptible intercellular spaces. 
The ventral region is occupied with loose parenchyma. The walls of the collen- 
chyma-like tissue are characterized by considerable contractility in longitudinal 
direction. The papillose epidermis of the ventral side is practically impermeable, 
but if carefully removed and the exposed tissue submerged in solutions of varying 
osmotic strength it appears that a curvature of the filament results from the plas- 
molysis and consequent contraction of the collenchyma-like tissue. The author’s 
explanation agrees with that of PFEFFER, namely, filtration under turgor pressure, 
and whatever causes the escape of water from the cell permits contraction of the 
cell walls and results in curvature. The author thinks that the papillose epi- 
dermis of the ventral side cooperates with the collenchyma-like tissue in con- 
traction. Why the contact stimulus should cause filtration under pressure is no 
more accounted for than before. The filaments of Centaurea will endure sur- 
prising transpiration without loss of contractile capacity—RAYMOND H. Ponp. 
The fertile spike of Ophioglossaceae.—CAMPBELL?3 has studied the mor- 
phology of the sporophyll and the distribution of the vascular bundles in the 
three genera of Ophioglossaceae, abundant material having been obtained during 
his recent visit to the oriental tropics. A study of the development of the sporo- 
phyll suggested that the “fertile spike” is the terminal structure rather than an 
adaxial branch. This view was confirmed by the distribution of the vascular 
bundles of the leaf, those supplying the spike evidently not being given off from 
the main bundles of the petiole as branches, but being a continuation of the main 
bundles. From this point of view, the fertile spike terminates the main axis, 
which bears the foliage blade asa lateral member. This accords with the author’s 
previously expressed view that Ophioglossum is perhaps the most primitive of 
the pteridophytes, the “fertile spike” being most naturally connected with such 
a structure as the sporogonium of Anthoceros. ‘This hypothesis assumes that, ~ 
by the development of a root from the lower part of the sporophyte and a com- 
plete septation of the sporogenous tissue of the sporogonium, so that something 
resembling the spike of an Sp scien resulted, there would be formed a plant 
not very unlike O. simplex.”—J. M 
A cotton fungus.—According to a preliminary paper by Batt,?4 the “sore- 
shin fungus” which occurs on cotton and other plants in the United States is also 
ry common on cotton seedlings in all parts of Egypt. The fungus is said to be 
responsible for most of the resowing which is necessary in Egpytian cotton 
fields e damage, which is not great, is caused partly by rotting of the seed- 
23 — D. H., Studies on the Ophioglossaceae. Amer. Nat. 41:139-159- 
figs. 17. 190 
ss nie W. L., The oe of a simple parasite. Reprint, Jahrb. Khedi- 
vial Soc. pp. 25. pls. 6-7. 
