236 Royal Academy of Berlin. 



Read a paper by Charles Lush, M.D., F.L.S., on the identity 

 of three described species of Acacia. 



The species are, A. Lebbek of Linnaeus, speciosa of Willdenow, 

 and Sirissa of Roxburgh, which Dr. Lush has satisfactorily proved 

 to be identical. They will all range under Acacia Lebbek, which, 

 although extensively cultivated as an ornamental tree in Egypt, is 

 not indigenous ; and Dr. Lush suspects that it had originally been 

 imported from the Deccan, and its Indian name, Serisch, as recorded 

 by Forskal, appears to support this opinion. The leaves on the 

 same tree vary in the number of the pinnae. 



PROCEEDINGS OF THE ROYAL ACADEMY OF BERLIN.* 



Feb. 20, 1837. — M. Horkel read a paper on the structure of the 

 seed and on the germination of the genus Pistia. A specimen of 

 Pistia Stratiotes, Bonpl. (not of Linnaeus), from Brazil, preserved in 

 spirit, had enabled him to add a few additional notices to what had 

 already been published by Mirbel, Turpin, and Lindley respecting 

 the seeds of other species of Pistia. 



It is easy to conceive, that as his precursors had employed for their 

 examination only dry seeds, in which the true form is not restored 

 by any length of moistening, they have described and figured it as 

 cylindrical and very rugose, while it is pear-shaped and smooth, as 

 Louis Nee, who had the opportunity of observing fresh Pistia seeds 

 in many quarters of the globe, describes it, comparing its form to 

 that of a small pestle. This pear-shaped form of the seed originates 

 through a considerable thickening of the spongy testa at the free or 

 micropyle extremity of the seed, while the chalaza extremity becomes 

 gradually thinner and passes quite imperceptibly into the thick short 

 funiculus, whence originates a considerable cavity at the separation 

 of the ripe seed in the proximity of the chalaza. The third reticulate 

 coat of the seed described by Mirbel is not present, but there are on 

 more than the two ordinary ones, testa and membrana interna. The 

 first of these was considered, quite erroneously, by Turpin as an arillus. 



Although M. Horkel found on his specimen ovula and seeds in all 

 their stages of growth, so that he could even plainly detect the course 

 of the pollen tubes from the style into the ovula, yet much of the in- 

 terior of the full-grown ovula had become opake, from the too great 

 strength of the spirit, rendering it impossible for him to give a com- 

 plete history of the development. However he saw thus much of it, 

 that the nucleus is very early obliterated by the rapid extension of 



* Translated from the Bericht liber die Verhandlungen der kbnigl. Aka- 

 demie der Wissenschaften zu Berlin. 



