SECRETION. 
93 
probably owing to the greater circumference of the leaves, in 
which the distribution takes place more rapidly than in the 
smaller leaves. 
This familiar phenomenon has found, in this instance, an 
excellent observer. That the vessels, the spiroids, namely, 
which are situated in the leaf-nerves, carry the juice of nutri- 
tion rapidly from one place to another, conducting it finally to 
those points where it is necessary for the nourishment of the 
plant, is convincingly demonstrated in these observations. 
Remarks on the Formation of Crystals in the Vegetable 
World, have been published by Unger in the Ann. of the 
Vienna Museum of Natural History, vol. ii. p. 1. After hav- 
ing treated generally of their occurrence, he gives drawings of 
crystals in the cellular tissue of many plants, which, however, 
are not sufficient for their determination, as the sizes of the 
angles are not stated. This is followed by some chemical 
researches. He dissolved crystals of Piper hlandum, Ficus 
bengalensis, and Maranta zebrina, in nitric acid, and neutra- 
lised the liquid with ammonia. The precipitate was heated in 
a platina crucible ; that of the crystals from Piper blandum 
was alone coloured brown. After having been heated, effer- 
vescence of all of them took place, on being treated with acids. 
The crystals consisted, in all three cases, of a vegetable acid, 
and most probably of lime ; the acid in the crystals of Maranta 
zebrina and Ficus bengalensis were oxalic acid ; the acid, 
however, in the crystals of Piper blandum must have been a 
different one. 
Payen has instituted some researches on the Calcareous 
Precipitates, and Precip>itates in General in Plants. (Compt. 
Rend., 1840, vol. ii. p. 401). The stalked, club-shaped sub- 
stances in the species of Ficus, which are covered with calcareous 
precipitates, and which Meyen first observed, have been inves- 
tigated by the author in Ficus ferruginea, laurifolia, benga- 
lensis, nymphceifolia, elastica, Carica, religiosa, and reclinata; 
further in Parietaria officinalis, where they are very large ; 
in P. lusitanica and arbor ea, JJrtica nivea, and Forskalea 
tenacissima. The cylindrical concretions from Celtis australis, 
and the pear-shaped ones from C. missisipensis were similar ; 
485 
