8 Tans ley and Chick . — Notes on the 
channels. There can scarcely be a qyestion here of mechanical 
function, and there seems to be no demand in this type of 
plant-body for a special channel for conducting formed food- 
substances, a process which is no doubt carried on efficiently 
enough by the cortical cells. On the other hand the position 
of these strands, and the fact that their walls though thin are 
lignified, agree perfectly with the strands found in the other 
members of the genus which do in fact conduct water. If 
the inference is sound, we have in this Malahide plant the 
most primitive water-conducting tissue or ‘ hydrom 1 ’ known. 
Whether Carrington’s var. / 3 , Wilsoniana is a good constant 
variety, and whether, if so, these strands are always found in 
it, are questions we are unable to answer. If the answer 
should be affirmative, the plant certainly deserves specific 
rank on the ground of this well-marked anatomical feature 
alone. If not, the conditions under which the strands appear 
would form the subject of an investigation of great interest. 
As we could not hear of a certain locality for the cosmo- 
politan Pallavicinia Lyellii in this country, Professor Howe, of 
Columbia University, very kindly sent us living specimens 
from Van Cortlandt Park, New York. The thallus of this 
species is band-shaped and wavy, about 3 to 5 mm. or more 
broad, with a thick, cushion-like midrib, -5 to 1 mm. in 
diameter. In transverse section the midrib in the specimen 
examined, *5 mm. broad and -25 mm. deep, is seen to be 
nearly flat on the dorsal surface, which is continued into the 
wings ; these consist of a single layer of nearly cubical cells 
packed with chlorophyll, and forming the chief assimilating 
tissue. On the ventral surface the midrib is rounded, and 
some of its surface-cells are extended into thin-walled rhizoids, 
though these are not very numerous, so that in many trans- 
verse sections none are seen. The cells of the surface-layer 
are small, square in section, and full of chlorophyll ; the 
deeper cells are variable in size and shape, several of those 
nearer the surface being full of chlorophyll, but most having 
1 Potonie, Ueber d. Zusammensetzung der Leitbiindel bei den Gefasskryptogamen. 
Jahrb. d. kon. bot. Gartens, Berlin, Bd. ii, 1883. 
