88 
POPULAR SCIENCE REVIEW. 
discovered near Duma, in the western slope of Lebanon, near to the one dis- 
covered by Mr. Tristram himself. 
The Newfoundland Heather . — About a year ago we pointed out in our 
Summary that the Calluna vulgaris, or common British heather, had been said 
to have been found growing in North America. Some interest attaches 
to the subject, and therefore we are glad to direct the attention of our 
readers to a paper by Dr. Seemann in the Journal of Botany (No. xlvi.) 
upon a comparison between the American and the British species. Dr. See- 
mann observes that Dr. Moore, of Dublin, who cultivates the two varieties 
side by side, noticed that, u whilst the Newfoundland one always suffered 
from frost, and turned brown during the mild Irish winter, the common 
British form growing by its side was unaffected by cold, and preserved its 
usual green colour . ” Dr. Seemann states that, though at first sight the 
plants seem to be as different as possible from each other, there is never- 
theless considerable difficulty in indicating the structural differences between 
the two. Dr. Seemann gives the following as the chief points of difference 
between the British and American specimens. The leaves of the New- 
foundland plant are always closely adpressed to the stem ; those of Calluna 
vulgaris are generally patent ; the pedicels of the Newfoundland plant are 
always naked ; those of the true C. vulgaris are, especially those of the 
lowest flowers, foliaceous, so that they form little branchlets, terminating- 
in a solitary flower; whilst the sepals and petals of the Newfoundland 
plant are ovate and indexed, those of the common British heather are 
rather oblong and not indexed. Again, in the Newfoundland plant the 
tip of the flowering branches does not put forth fresh shoots whilst the 
flowering lasts ; but in the common British heather a fresh shoot issues 
when the flowering is at its height. 
The History of the Potato. — In a paper lately read by Mr. Crawfurd, on 
u The Relation of Plants to Ethnology,” a very short but complete account 
was given of the introduction of the potato into Europe. The potato is still 
found on the western slopes of the Andes, the tubers, however, being no 
bigger than the common filbert. Even the Indians, said Mr. Crawfurd, cul- 
tivated the potato before the arrival of the Europeans. It was first brought 
from America to Ireland, where it was cultivated in 1586 ; but it is said to 
have been introduced into Spain and Portugal even before this date. From 
Ireland it found its way to the Low Countries and to Germany, and from 
Spain it reached Italy and France. It is an object of cultivation in Asiatic 
countries only where Europeans have colonised or settled, and there chiefly 
for their consumption, and only since the beginning of the present century. 
It is successfully cultivated in Australia and New Zealand, which produced 
no esculent farinaceous root at all, not even the yam, the taro, or the 
manioc. 
Functions of the Stomata of Leaves. — The ordinary theory that the stomata 
of leaves are the bre ath i n g- o rgan s through which the carbonic acid is decom- 
posed has met with two new opponents in MM. Duchartre and Boussingault. 
These observers allege that the quantity of carbonic acid decomposed by the 
leaves of plants has no relation to the number or superficial extent of the 
stomata. They further state that in the case of fruits the green parts de- 
compose carbonic acid, and yet contain no trace of stomata. 
