282 DR. M. J. SCHLEIDEN OX PH YTOGEXESIS. 



observations can alone impart to them their proper scientific 

 value. Perhaps, however, I may succeed by these remarks in 

 drawing attention to this highly important subject. 



Since no real advance in the acquisition of knowledge results 

 from the attempt to explain processes in nature hypothetically, 

 and least of all, where all requisites for a tenable hypothesis, 

 namely all guiding facts, are wanting, I may omit all historical 

 introduction ; for as far as I am acquainted, no direct experi- 

 ments exist at present on the origin of the cells of plants. That 

 Sprengel's supposed primitive cells are solid granules of amy- 

 lum, has long since been demonstrated. To enter into Raspail's 

 observations seems to me to be inconsistent with the dignity of 

 the science. He who feels any desire to do so may turn to the 

 Avork itself. 



The only researches connected with this subject, the highly 

 important ones of De Mirbel, I shall have occasion to advert to 

 subsequently, since even he does not make any mention of the 

 progress of the formation of cells. It is to be regretted that 

 Meyen, who, perhaps, has studied vegetable anatomy more 

 extensively than any one up to the present day, has confined 

 himself almost solely to the examination of developed forms, 

 and has not yet brought the formative process itself in any 

 degree into the field of his inquiries. I have still many doubts, 

 the solution of which I had hoped to have found in his Vege- 

 table Physiology, but found them not. 



It was Robert Brown, who, with his natural genius and 

 comprehensive power of mind, first conceived the im^jortance of 

 a phjcnomenon which, although observed previously by others, 

 yet had been lefi; totally unregarded. He found at first in the 

 OrcliidecE, in a great portion of their cells, chiefly in the epi- 

 dermis, an opake spot designated by him areola or nucleus of 

 the cell. He subsequently pursued this phccnomenon in the 

 eai'lier stages of the poUinic cells, in the young ovulum, in the 

 stigmatic tissue, not merely in the Orchidecc, but also in many 

 other Monocotyledons, and even in some Dicotyledons. It was 

 natural that the constant presence of this areola in the cells of 

 the very young embryo and in the newly originated albumen 

 should strike me in my extensive researches respecting the 

 development of the embryo; and thus, from the consideration of 

 the vai'ious modes of its occurrence, the thought very naturally 

 arose, that this nucleus of the cell must stand in a close re- 



