42 



great difference in the observations and in the views on the 

 structure of the leaves of Sphagnum ; several other botanists 

 and myself regarded the fibrous formations occurring on the 

 inner surface of the cellular walls of those plants as spiral 

 fibres, similar to those which occur in the cells of anthers ; 

 and M. Mohl, who, on the contrary, declared these spiral fibres 

 to be partial thickenings of the cellular walls, has at pre- 

 sent also adopted the former view, the correctness of which 

 can no longer be doubted. It is however very different with 

 respect to the observations on the occurrence of large round 

 apertures on the partitions of the cells in Sphagnum : Molden- 

 hauer was the first to observe them ; I denied their existence, 

 which however was again confirmed by M. Mohl. Although 

 I again took in hand my plants of Sphagnum, and observed 

 with a microscope by Ploessl, yet I could never find the al- 

 leged pores, but either perfectly symmetrical septa, as I have 

 correctly figured them in my Vegetable Physiology, i. pi. III. 

 figs. 10 and 11, or such as possessed circular, verrucous pro- 

 minences, which seen from the side projected beyond the sur- 

 face of the cells ; but seen from above, presented mere cir- 

 cles, indicating the circumference of those verrucous promi- 

 nences. These circles were regarded by Moldenhauer and 

 Mohl as open apertures, whereas I had always observed them 

 closed, even when I had coloured the cellular partitions brown 

 by means of iodine. M. Mohl * replied to these statements 

 very fully and forcibly in a separate Inaugural Dissertation, and 

 maintains the existence of pores in the septa of the cells of 

 Sphagnum-, however, as I first noticed during the past summer, 

 both conflicting parties are right and wrong. A very great 

 quantity of forms of Sphagnum, and among them principally 

 Sphagnum acutifolium, which grows about Berlin in very beau- 

 tiful specimens, exhibit quite smooth and unruptured septa, 

 and I have never found pores in them, although I have made 

 frequent observations on them. Other forms, on the contrary, 

 exhibit the verrucous circular prominences; and others, among 

 which is the common Sphagnum palustre, present large circular 

 pores in the septa, which originate in the falling off of the 



* Anatomische Untersuchungen iiber die porb'sen Zellon von Sphagnum, 

 Inaug. Dissertation von Ph. Schlayer. I regard Prof. Mohl as the author 

 of this, as well as of all other dissertations occurring in this report. MEYEN. 



