117 



assembly itself, giving a pretty complete explanation of the 

 function of the micropyle and the structure of seeds, leaving 

 out of question the researches of Rob. Brown. There is, it is 

 true, a great deal to be observed on this subject in special, but 

 in general we have so clear a knowledge of it that such a dis- 

 regard of the observations of others must highly astonish us. 



M. Dutrochet describes in the second part of his work the 

 ovule of various plants, e.g. of Amyydalus communis, Evony- 

 mus europaus, Pisum sativum, Fagus Castanea, Galium Apa- 

 rine, Spinacea oleracea, Mirabilis Jalappa, Nymphaa lutea, 

 and Secale cereale, and shows that he is well acquainted with 

 a difference in the number of the envelopes of the seed in va- 

 rious plants ; but he nevertheless employs the terms for these 

 parts invented by M. de Mirbel, which in the present state of 

 observations are no longer suitable. M. de Mirbel has highly 

 advanced our knowledge of the structure of the seed, previous 

 and subsequent to impregnation, as every botanist will admit ; 

 and, though I would no longer recognize the terms which this 

 learned naturalist has advanced to render the subject intelli- 

 gible, it must not be regarded as a censure cast upon those 

 admirable researches. 



At the conclusion of the memoir, M. Dutrochet relates his 

 observations on the formation of ergot ; he does not con- 

 sider it to be a fungus, but a diseased development of the grain. 

 But it appears to him probable, that this diseased development 

 of the grain into ergot is in consequence of the presence and 

 increase of a microscopic fungus, which should be placed by the 

 side of Uredo. I cannot however concur in this view, in con- 

 sequence of my observations on the subject. 



Another important work of M. Mohl* relates to the mor- 

 phological signification of the organs of propagation of those 

 Cryptogamia which are provided with leaves. In these inquiries 

 he starts from the two following morphological positions, as 

 their correctness is of the highest importance in every explana- 

 tion of the organs of fructification of the Cryptogamia. They 

 are: 



1 . That the anther in Phanerogamia is not formed by the 

 involution of a leaf, and that consequently the pollen grains 



* Morphologische Betrachtungen iiber das Sporangium der mit Gefassen 

 versehenen Cryptogamen. Eine Inaugural Dissertation. Tubingen, 1837. 

 8vo. 



