The daily morning journal and courier., 1901-06-27
HANNA.

Identified as a Lichen Plentiful in
 Arabia and the Sahara.
 Tt is mammal" exclaimed the people
 of Israel as they gathered the food
 which seemed so miraculously to ap-
 pear at their very feet in answer to
 their cry for sustenance, but though i they ate and were satisfied, yet, we are
 told, they twist not what is was'
 And during the ages that have passed 1 since it's first appearance on that me-
 morable dewy morning in the Wilder
 ness of Sin men have declared again
 and again that they twist not what it | was" that thus fed the Israelites in
 their need, though numberless conjec- | lures have been made and discussions | held on the matter. The chief opinion
 which had sway for a long time was
 that mama was the sap of the tama-
 risk; but now authorities, seeing in the ! light of widening scientific knowledge
 declare that mama was without doubt a certain lichen Gecanora esculenta)
 This is borne out by the fact that well authenticated rains of mama, abso- lutely believed by the inhabitants to be | showers from heaven. have been re- ported al least six times during the present century by reliable travellers in
 the east, and the descriptions of the de- posit given in precise present day lan guage leave no doubt upon the point, . Y. If a piece of mama be exam
 ined under the microscope it's peculiar compound structure can be clearly seen; there is a delicate network of in
 terlacing fungal threads glistening in
 the light, while inclosed in their mesh es are number of round bright green cells, each tiny algal plant. Thus fungus and alga live together in most intimate connection, the fungus being in the mama lichen the leading spirit, though this is not the case in every lichen, for in some of these organisms the development of the green plant is the factor determining the form which will be taken.
 It may be asked fresh manna-lichens arise, seeing that it is difficult to imag
 inc a frequent coincident meeting of a particular fungus and particular green plant. But, granted the meeting has once taken place, the rapid repro duction is easy to understand At cer- tain times in the year a yellowish dust appears in little green cups growing on the surface of the plant, and each of the grains of dust is minute bundle containing a few of the white filaments and a few of the green cells wrapped up together, so that wherever this dust may fall each grain can become new manna-lichen. There is, moreover, second method of reproduction in which the fungus alone takes part, and sends out tiny offspring to take their chance in the wide world of finding a suitable host as their parent has done; but the details are complicated and at present involved in some obscurity.
 Thus then Lecanora esculenta-man- na--is in it's very nature one of the most remarkable phenomena in the vegetable world. It is found over great tracts of southwest Asia, near Constan- tinople. in the Crimea. the deserts of Arabia, in the Sahara and the deserts of Algeria. It is easy to pass it by un- noticed for it is grayish yellow in color and grows on gray limestone rocks and fragments of rock in the form of a wrinkled crust, which seems to a casu- al observer part of the very rock itself and needs special care to distinguish it. Cut through it is white like corn within dry and powdery; it is, moreover, ex- tremely light in weight It is obvious that there is not much nourishment to be obtained from the bare face of the limestone rock-hence all the suste- nance of the two plants must be ob- tained from the atmosphere and the rain by the little green plant, which | must thus work doubly hard to be able tc pass on sufficient food for it's part ner's living in addition to providing it's own. By degrees, as it grows older it becomes loosened or even detached | from the rocks, and then when the sud den whirlwinds and violent storms | which affect many of these regions blow the featherweight pieces of lich- en- crust are torn up and blown into the | air at the mercy of the wind and car ried hither and thither, it may be for | immense distances. The rains, too, that descend with such sudden vehe- mence sweep it away into water chan | nels, where it Is borne along on the stream and deposited in hollows and | left there in heaps when the water sub | sides. At times, too a waterspout will ! gather it up, carry it along, and ulti- mately deposit it in place where hitherto it had been practically un- Clarke Nuttall in the Sun day Magazine.