Bibliographical Notices. 4^1 



passes on to the consideration of the vesicles (Blasen) in Utricularia, 

 the structure of which is accurately expounded. They are at first 

 filled with a slimy liquid, the place of which is subsequently occu- 

 pied by air. Then follow the ascidia of Nepenthes, which like- 

 wise, when young, contain air only. The secretion of water at the 

 apices and margins of the leaves of many plants is not considered to 

 be a secretion, nor could the author find the apertures described by 

 Schmidt, which produce this. In the second chapter those organs 

 are treated of which secrete within the cellular tissue mucus, gum, 

 oil, balsam, and resin. The author regards the resin-canals as 

 widened interceUular passages, having no epidermis, and whose con- 

 tents are formed by the immediately adjacent cells. In Rhus typhina 

 there is no latical sap (Milchsaft) nor vessels, but passages with a 

 liquid resin containing much turpentine. In the Umbellatce there is 

 also evident in summer a formation of passages containing an oily li- 

 quid. The oil vessels in the seminal envelopes of the Umbellatcepoasess 

 the same structure, but are smaller than the former. The mucus 

 and gum passages are of similar origin, but are shorter and without 

 laevigated walls. They occur of a very large size in the Cactea, 

 Malvacece, and Zamiee. ITie glands are treated of in the third 

 chapter, in which Guettard's observations are maintained against 

 the views of De CandoUe. The author divides the glands into ex- 

 ternal and internal, the former again into simple and compound. 

 The simple are petiolated or nonpetiolated, in the first case similar 

 to glandular hairs ; here the formation of hairs is shortly touched 

 upon. The petiolated glands of a number of plants are described 

 and in part figured ; they are claimed for the Chenopodece, where they 

 are said to form respiratory and secreting parts, and the glandular 

 cell to be formed last on the hair ; even when a compound gland 

 exists on the hair, it is formed last. The simple nonpetiolated glands 

 comprise the glandes miliaires of Guettard, or stomata ; the author 

 at present confesses that they possess apertures, but that the two 

 cells act like a kind of sphincter (Schliessmuskel) , and at the same 

 time have the function of glands. Of the compound glands several are 

 accurately represented, among others those ofDictamnus, which more- 

 over have a cavity for the secreted matter; those of the hop, the 

 globules contained in which on their exit into the water present an 

 extremely lively and free movement ; those of Ribes, Galium, &c. 

 The organs secreting a caustic substance in Urtica, Jatropha, and 

 Loasa, and the rotation of the cellular sap in the two latter, are then 

 described, after which follow the compound internal glands without 

 cavities of secretion ; when the cells contain small drops of oil or 



