30 



stance, those of Strelitzia Regina, Papyrus antiquorum, Rheum 

 undulatum, Yucca gloriosa, Musa paradisiaca, and M. coccinea, 

 and those of Maranta zebrina, and has treated this point more 

 crystallographically. Many of these statements do not agree 

 with my observations, but a short time will prove the correct- 

 ness of the one or the other ; it appears however to me that a 

 rich field is here opened to the crystallographer, for frequently 

 the most beautiful crystals with all their variations are innu- 

 merable in the same plant. The crystals of obtuse form, which 

 M. Unger has figured from Strelitzia Regina, as well as most 

 of those in Maranta zebrina, and in the pith of the Peperomics 

 and species of Piper, consist of gypsum; in the latter plants I 

 have found tjiem along with crystals of oxalate of lime. 



As an appendix to the memoir on the crystalline formations 

 of plants, M. Unger has published some notices on the milk sap 

 or vital sap vessels (proper vessels) of plants, and at the same 

 time promises on some future occasion to show how the cir- 

 culation of the sap, which takes place in these vessels, is gene- 

 rally carried on. Probably M. Unger will be able to explain 

 this phenomenon which has hitherto remained problema- 

 tical. He also thinks he has put an end by his observa- 

 tions to the dispute respecting the independence of the milk 

 sap vessels by the following statements : " The milk sap ves- 

 sels are only a portion of the vascular fasciculi (those bundles 

 of organs are here intended which in most plants become 

 lignified, and on that account are termed ligneous fasciculi) : 

 they form, it is true, one system of sap-conducting canals, 

 connected by frequent anastomosis, but nevertheless appear 

 to be more closely allied to the parenchyma than to the sy- 

 stem of vascular fasciculi." This view is said to be favoured, 

 first by the position of these vessels in the bark or medullary 

 substance,and secondly by the genesis of thevessels themselves. 

 The origin of the vessels however rests on the following obser- 

 vations : M. Unger observed in a longitudinal section from 

 the medulla of Ficus bengalensis, which is represented in fig. 1. 

 of the memoir on the crystalline formations in plants, several 

 parenchymatous cells placed perpendicularly on one another, 

 differing from the adjacent cells by their contents, which re- 

 sembled that of the other milk sap vessels. This, says M. 

 Unger, can evidently be regarded as nothing else than the 



