and the Nature of the Earliest Pores. 283 



which in A was a nucleolus has in B passed into the state of 

 nucleus. The segments in B are nucleolated nuclei. Fig. C 

 represents a stage somewhat more advanced ; the nucleus is 

 vesicular (its nucleolus parietal). In D such segments as those 

 at B and C have divided into groups of nucleolated nuclei, g. 

 In fig. E some of these groups remain ; others have broken up 

 into single nucleolated nuclei. The latter are arranged so as to 

 lay the foundation of a membrane, h. This membrane is the 

 primary membiane of a cell. (Its elements usually appear first as 

 mere globules, in which no nucleolus can be discerned, and 

 which are too minute for examination.) At a later period I 

 noticed the state fig. F. In F were nuclei such as those at h 

 in E, and the nucleoli were most regularly equidistant. Up to 

 this period the formation of the membrane is incomplete, and 

 it continues incomplete until fibre forms. The nucleolated 

 nuclei A of E and F are the elements of fibre. 



From these drawings it will be seen that, according to my 

 observations, the cell-membrane does not form around the 

 nucleus, but is the outer part of the nucleus in an altered state. 

 The nucleus, in fact, passes into the condition of a cell. In 

 order to this it becomes segmented. The segments are usually 

 globules or granules, too minute for examination. These coalesce 

 and thus lay the foundation of a membrane. But there is one 

 nucleus — that in fig. A — the segments of which are of sufiicient 

 size to show distinctly that they are nuclei themselves, each of 

 these having its nucleolus, fig. B. The great size of the seg- 

 ments of this nucleus, no doubt, has reference to the functions 

 which the cell it passes into is destined to perform, as well as 

 to the enormous magnitude which it attains. That cell is my 

 ovisac. It remains to add, that, having discerned traces of a like 

 process in the formation even of the most transitory cells, I be- 

 lieve that the membrane of every cell has the same mode of origin 

 as the membrane of the ovisac. 



When at Giessen in 1852 I had the pleasure of reading the 

 work of Baron Liebig, entitled " Untersuchungen iiber einige 

 Ursachen der Saftebewegung im thierischen Organismus,'1848/^ 

 and pointed out to that justly celebrated man the nucleoli in my 

 drawing now reproduced in fig. F, stating to him my belief 

 that it represented pores. I am still of the opinion that in the 

 half-formed state of membrane fig. F, nucleoli are the only pores. 

 And in proof that such is the case, have only to refer to what I 

 have been maintaining since the year 1840, when, in the Phil. 

 Trans, for that year I showed a suctorial power to be manifested 

 by the protrusion of the parietal uncovered hyaline nucleolus of 

 the germ spot, to take up the equivalent, corresponding, or 

 counterpart from the spermatozoon ; and to drawings I gave in 



