of Lathraea elandestina, 41 1 



characters to natural classification, that all the essential organs 

 of a certain number of the principal types of the vegetable king- 

 dom should be examined with care. Many facts considered as 

 general would lose this universality, and the greater or less fre- 

 quency of the exceptions would soon establish the value of cha- 

 racters and the importance of such or such a point of organiza- 

 tion. 



The memoir of M. Duchartre on LathrcBa clandestina is an ex- 

 cellent example of this kind of investigation, in which many 

 points are treated in a very complete and satisfactory manner, 

 and in which only a small number of gaps would remain to be 

 noticed. 



But this memoir acquires an additional interest from the na- 

 ture of the plant which is the subject of it. The mode of exist- 

 ence of parasitical plants is always an interesting problem to solve, 

 knd the anatomical examination of their organs must serve as a 

 starting-point for physiological researches. 



Several of these vegetables have already been the object of 

 minute research, among which must be cited in the first rank 

 that of Mr. R. Brown on Rafflesia, then those of M. linger on 

 parasitical plants in general, of M. Goeppert on the Balanophor(B, 

 and lastly, the researches of Mr. Bowman on another species of 

 the same genus Lathrcea, viz. L. squamaria. But, if we except 

 the first of these memoirs, the other treatises have almost had 

 for their sole object the mode of implantation of the parasites on 

 the plants from which they draw their nourishment, or some pe- 

 culiar points of their organization. M. Duchartre, on the con- 

 trary, has proposed to study successively all the organs of the 

 curious plant which forms the subject of his researches ; he pre- 

 sents an anatomical monography of it, and this step has led him 

 to discover several important facts in the structure of this species. 



We shall follow him in the examination of the various organs 

 of vegetation and reproduction, noticing rapidly the points by 

 which the organization of this plant appears to differ from that 

 of the vegetables which have already been studied by other ana- 

 tomists ; and we may observe, that we have been able to verify the 

 majority of the facts advanced by M. Duchartre, and represented 

 in the numerous drawings which accompany his memoir, by 

 means of fresh specimens, or specimens preserved in alcohol. 



The structure of the stem is first studied by M. Duchartre; he 

 finds in it, as in all the stems of Dicotyledons, the pith, the lig- 

 neous system and the cortical system formed of the liber and of 

 the cellular envelope ; but he notices two characters which appear 

 to remove this plant from the usual structure of these vegetables. 

 The first consists in the absence of a medullary sheath, that is to 

 say, of a first interior zone of vessels of a different nature to those 



2F2 



