TRANSACTIONS OF THE SECTIONS. 89 
On an undescribed Alga allied to Coleochete scutata. By Professor ALLMAN. 
This paper contained a description of an alga discovered in certain subalpine streams 
in Ireland. It presents the appearance of small perceptibly elevated discs of a dark 
green colour, varying in size from about half a line to three lines in diameter, and 
attached to the upper surface of stones in the most rapid part of the current. When 
several plants grow upon the same stone they often become confluent, and form 
patches of indefinite figure and extent. Each plant is of a firm, almost cartilaginous 
consistence, and an ordinary lens shows it to be furnished with a margin divided into 
rounded lobes. Under a higher magnifying power the structure is found to consist 
of numerous disc-shaped laminz, placed one over the other with an imbricated 
arrangement, the margin of each projecting beyond that of the superposed lamina. 
The lowest lamina is always the youngest, and each consists of many dichotomously 
branched series of nucleated cells, which radiate from a common centre, and are 
united at their edges into a continuous frond. In no specimens, though examined 
at various seasons and at different stages of development, were the sheathed seta of 
Coleochete detected. From the only described species of Coleochete, therefore, the 
present plant differs in its lobed outline, in its imbricated structure, in its firm con- 
sistence, in its large size, in the absence of setz, and inits habitat. The author be- 
lieves it to be generically distinct from all hitherto described forms, though standing 
near to Coleochete or Phyllactidium; he proposes for it the name of Sorodiscus 
rivularis. 
On the means of obviating the ravages of the Potuto Disease, by raising fully- 
grown healthy Potatoes from seed in one season. ByW.Hocan,M.R.LA. 
4 
The method was discovered by M. Zander of Boitzenburg, who has practised it 
for six years with the greatest success *. 
The following extracts are from M. Zander’s published letter :-— 
“I first raised potatoes from seed six years ago. I sowed an eighth of an ounce, 
and obtained nearly seven sacks of fully-grown, perfectly sound potatoes, although 
in the same year almost all the potatoes in my neighbourhood were affected by 
pock-mark and dry-rot. I have regularly raised potatoes from seed ever since, 
_and they have remained sound during the whole time, and last year (1845), when 
the disease had spread over all Europe, and attained the greatest virulence in this 
neighbourhood, those potatoes which I had previously raised from seed, as well as 
those of the preceding year, continued perfectly exempt from disease. I have given 
potatoes raised from seed to my friends and acquaintances, and those have also 
remained perfectly free from the universally prevailing disease. From an ounce 
of seed you may raise upwards of fifty sacks of potatoes: the smallest crop I ever 
had from half an cunce was twenty-four sacks. 
“The seed is saved in the following manner :—the berries should be gathered in 
autumn, before the frost sets in, and be preserved in a dry place, where frost cannot 
reach them, until the end of January, when the berries should be broken by the 
hand and placed in a tub or other vessel for six or eight days to ferment ; water should 
then be thrown on them and well-stirred in order to separate the pulp and husks 
from the seed, which should then be dried and cleaned, and kept in a warm dry 
place until the middle of March. 
“In the middle of March or beginning of April, the seed should be thinly sown ina 
hot-bed, and by the middle of May there will be fine healthy plants which may be 
put out into the field; care should be taken to put them out before they form tu- 
bers, and the seed-bed sliould be kept moderately moist while they remain in it. 
They should be planted out after rain, and be put at about the same distance from 
one another as potatoes generally stand in the field.” 
The foregoing extracts contain two most important statements :—one, that it is 
possible to raise an abundance of fully-grown potatoes from seed in one season; and 
the other, that such potatoes will resist and escape the generally prevailing disease, 
for six years at least. Mr. Hogan then entered into a statement of his own observa- 
tions on this mode of cultivation in two widely-separated lecalities in Germany, 
* In a report made by M. Zander, he states that his plan was equally successful with the 
crop of 1846. 
