58 



dicotyledonous plants, one the nodus integer, from all parts 

 of which the fibrovascular tissue proceeds into the leaf; 

 the other the nodus partialis, where the fibrovascular tissue 

 passes into the leaf at one point only. The nodus integer 

 is universal in the order, and Dr. Grisebach considers that 

 by this character Gentianacese are certainly known from 

 Cinchonace£e, Spigeliacese, and others. 



The organization of the flower of Swertia perennis and 

 Gentiana lutea, is traced from the earliest period when it is 

 distinctly visible up to the state of maturity. He finds the 

 petals originally distinct, although eventually consolidated 

 into a monopetalous corolla; the stamens distinct from the 

 corolla, and exactly like nascent leaves, although eventually 

 adherent to the petals; and the carpels also distinct; the con- 

 solidation of all these parts takes place subsequently, and 

 when the flower bud is about a line long. The placentation 

 of Gentiana lutea is from the beginning marginal to a car- 

 pel, and consequently at variance with the modern views of 

 Schleiden and Schykofsky, who deny the truth of the theory 

 that the origin of ovules is from the margin of carpellary 

 leaves, and refer all placentation to the growing point. 



The author next considers the limits, principles of division, 

 and affinities of the order ; he admits the small natural order 

 Columelliacese, and proposes a new order {Bolivariacece) to 

 include Bolivaria and Menodora. The geographical dis- 

 tribution of the order is considered at length, and at the same 

 time several general questions of interest in Botanical 

 geography are discussed at considerable length. It is found 

 that in all 343 Gentianaceous plants are known, and that the 

 only parts of the world in which some one or other does not 

 occur, are some islands in the Pacific, the tropical parts of 

 New Holland, Timor, Sumatra, and some other parts of the 

 Polynesian Flora, the deserts of Africa, the littoral of Vene- 

 zuela ; and that they have scarcely been found on the moun- 

 tains of Southern Europe. Of the species, 210 are tropical 

 and 133 are extratropical. 



The order is divided into 40 genera, distributed through 

 seven tribes; the detailed account of which is preceded by an 

 excellent analytical table of the genera, tribes and species. 

 Of Exacum 13 species are enumerated, of the beautiful genus 

 Sabbatia 11, of Erythrgea 17, of Lisianthus 33, and of Gen- 

 tiana, to which are reduced most of the genera separated by 



