IN THE GENUS TRICHIA. 55 
“T send you now a tracing of a sketch which I made several 
years ago. You will see that there are three distinct continuous 
spirals—not asperities, nor what the reviewer terms arcuate eleva- 
tions of the.cell-wall following a spiral direction. That there 
may be no doubt of the correctness of the observation, I enclose 
for Mr. Berkeley a few specimens of a Trichia collected here. 
I have had them some time, and they may not be so well adapted 
for observation as when in a living state. With a good micro- 
scope and a } object-glass the spirals are brought out quite dis- 
tinet, but a 1 may be necessary to enable one to count the num- 
ber of spirals. 
“Previous to observation, the specimen should be placed for a 
few hours in cold water, and then in boiling water. A shallow 
eye-glass would be best to use with the 1; otherwise, from the age 
of the specimen, the crossing of the threads will give the appear- 
ance of asperities. The size of the spores is at least four times 
too great to admit of there being a spore attached to each as- 
perity." 
Just after the receipt of Mr. Knights communication, a very 
learned paper, by Herr Wigand, appeared in Pringsheim's * Jahr- 
bücher für wissenschaftliche Botanik’ (published at the end of 
November 1861) on the genus Trichia and the nearly allied genus 
Arcyria, which differs principally from Trickia in the absence of 
spiral markings, or rather in the frequent substitution of rings 
instead of spirals. "The memoir is accompanied by numerous and 
most careful figures; and while it is quite convineing as to the 
threads bearing a very close relation to the spiral vessels of higher 
plants, it shows at the same time that they cannot be considered 
(at least, so far as herbarium specimens show) as vessels con- 
taining a free spiral thread, or even a raised spiral thread attached 
to the inner walls, but rather as having an elevation of their walls 
from within in a spiral direction, so as to leave a groove exter- 
nally between each volution of the spiral, —the hollow of the spiral 
itself being filled up afterwards, it should seem, by the deposition 
of new matter, though never in such a degree as to produce a 
raised spiral thread within the tube: they resemble, in fact, if I 
may be allowed to use the illustration, a male screw rather than a 
female. Asa proof of the deposit being subsequent to the spiral 
elevations, he adduces the fact that when first formed they are 
colourless, and that they only become opake at a later period of 
development. In certain states of Trichia furcata, as in Arcyria 
punicea, he finds rings instead of spirals, and, in some threads of 
