PROCEEDINGS OF SOCIETIES. 233 
Review’ of January, 1861, p. 8, that the reviewer states, in re- 
spect of spiral vessels, that it is true that all the species of Zrichia 
contains threads, all of which bear spiral markings, but the nature 
of the markings is still a subject of controversy. 
“ That these threads are true spiral threads I cannot doubt. I 
should, three or four years ago, have drawn your attention to the 
observations I had made on the subject, had I not been under the 
impression that the controversy had ceased, and the spiral nature 
of those cells been admitted. 
“ 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 Zrichia 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 1th object-glass the spirals are brought out quite dis- 
tinct, but a 4th 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 1th; otherwise, from the 
age of the specimen, the crossing of the threads will give the ap- 
pearance of asperities. The size of the spores is at least four 
times too great to admit of their being a spore attached to each 
asperity.”’ 
Just after the receipt of Mr. Knight’s communication, a very 
learned paper, by Herr Wigand, appeared in Pringsheim’s “ Jahr- 
biicher fiir wissenschaftliche Botanik,” (published at the end of 
November, 1861) on the genus 7ichia and the nearly allied genus 
Arcyria, which differs principally from Zrichia 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 convincing 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 contain- 
ing 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 
roduce 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. As a 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 opaque at a 
later period of development. In certain states of Trichia furcata, 
VOL. IV.—NEW SER. R 
