Mr. A. Henfrey on the Development of Vegetable Cells. 365 



that is to say, they were rather the only probable explanation of 

 the phenomena I had observed, than conclusions from an un- 

 broken series of examinations of the process in its successive 

 stages. 



I then gave it as my opinion, that the division of the parent- 

 cell into new cells is effected by the gradual folding inward of 

 the primordial utricle, which organ, in virtue of its peculiar func- 

 tion, secretes the septum within that fold ; the circular constric- 

 tion thus produced arriving finally at the centre, the septum 

 consisting of a double layer of cell-membrane becomes complete. 



It is chiefly with the view of confirming and substantiating 

 this opinion, and of supporting it by a reference to the evidence 

 in its favour which has since been furnished by other and inde- 

 pendent observers, that I have been induced to submit the pre- 

 sent remarks to your consideration. 



It may be remembered that I acknowledged last year that my 

 investigations had been directed in the channel which led to the 

 conclusions at which I had arrived by the elaborate observations 

 on the primordial utricle published by its discoverer Prof. Mohl. 



Toward the close of last year I was not a little gratified to find 

 that the further researches he had instituted into the office of 

 this structure had led him to adopt precisely the same view of 

 the process of cell-division in certain plants which I had ven- 

 tured to propound as of general occurrence. 



In the memoir on the Structure of Vegetable Cells*, in which 

 he first described the primordial utricle, Prof. Mohl stated that, 

 in the Confervse, this organ in cell-division became constricted 

 by a septum growing inward from the walls which finally sepa- 

 rated it into two ; but at that time he thought it probable that 

 this was a process totally different from that which took place in 

 the Phanerogamia, where he believed that the primordial utricle 

 separated into two before the production of the septum com- 

 menced. 



In a paper on the division of the cells of Confervce, published 

 in 1835, before the discovery of the primordial utricle, Prof. Mohl 

 affirmed that the septum grew inward directly from the cell-wall 

 and thus divided the cell into two. In the collected edition of his 

 memoirs published last year, he has re- written this latter paper, 

 correcting it in several important particulars in consequence of a 

 new series of observations he was induced to undertake to inves- 

 tigate the theory of cell-development advocated by Nageli. 



He there describes and figures the process of cell-division in 

 Conferva glomerata, and shows the production of the septum by 

 the primordial utricle exactly in the manner which I had indi- 

 cated as occurring in the hairs of the stamens of Tradescantia. 



* Translated in Taylor's Scientific Memoirs, Part XIII. p. 91. 



