244 REPORT ON THE TRANSACTIONS OF THE SOCIETY OF 



temporary species have appeared and disappeared at the same time, 

 the causes of appearance and disappearance having been the same 

 for all; 3d, neighboring formations present analogous forms. As 

 to exceptions which may occur with respect to the two last laws, we 

 have indicated a moment ago in what manner M. Pictet has sought 

 to account for them. 



Professor D. Candolle, in reference to the geological duration of 

 species, cited the investigations of M. Gaudir respecting the fossil 

 vegetables of the quaternary epoch in the repositories where certain 

 actual species of Europe are found — as the beech, for instance — 

 mingled with species which now live nowhere but in the United States; 

 this forming an additional exception to the law of the simultaneous 

 extinction of species. 



M. De Candolle made, besides, several communications relating to 

 vegetable physiology and botany proper, among which may be cited 

 an analysis of the researches of M. Duchartre on the organ which 

 produces the perfume in the vanilla, and a monographic study of the 

 family of Begoniaceas, of which one species (the begonia'' a/ptera) 

 presents the remarkable peculiarity of being furnished with parietal 

 and unequal placentas, contrary to what takes place in other species 

 of that family. He directed attention, also, to the existence of a 

 small insect which had, last year, occasioned the destruction of num- 

 bers of fir trees. 



In the province of botany we have still further to cite communica- 

 tions by MM. Choisy and Duby. The former described to us an 

 ivy-plant which he had observed near Peissy, growing on a horse- 

 chestnut, and remarkable for its exceptional dimensions as well as for 

 the singular fact that the branches hanging free bore leaves of a 

 beautiful form and different from those of the branches which had 

 attached themselves to the tree. He communicated, besides, a 

 memoir on two kinds of plants little known, assigned to the family of 

 guttiferae, {gynotroches and discotigene,) which both belong to the 

 island of Java. The second of these should continue to be retained 

 in the family of guttiferae; the first should be transferred to the family 

 of rhizophoraceae, as Blume and Bentham had already pronounced. 



M. Duby, besides some communications on the botanic investiga- 

 tions made by learned foreigners, read to the society a paper on a 

 species of dothidea, a cryptogam which grows on the Barbary jessa- 

 mine, (lyceum europceum,) and which in the same pustules passes 

 through three successive states, viz: a pulviscular state, a spermatic 

 and a thecasporic one. M. Duby, in presenting the history of the 

 development of this minute object, dwelt upon some questions of 

 taxonomy which connect themselves with that development, as well 

 as on the necessity, in the actual state of cryptogamy, of multiplying 

 observations on the evolution of the reproductive organs of cham- 

 pignons. 



It remains, in order to complete what we had to say on organic 

 natural history, to speak of transactions relating to zoology and ani- 

 mal physiology. First in order we find the researches of M. Edouard 

 Claparede on the organization of infusoria, presenting, after a review 



1 



