166 UTR1CULAR STRUCTURES. 



afterwards, since there is no trace of a membrane in the 

 young free cytoblasts, and the origin of these even appears 

 to contradict my view." If the origin of the nuclei could 

 be observed, this would afford the most decisive proof of 

 one or other of the theories. Schleiden indeed describes 

 the origin of the nucleus as a confluence or conglomera- 

 tion of mucilage-granules and nucleolar-globules. I cannot 

 agree at all in this opinion. The commencement of the 

 formation of the nucleus may be quite definitely distin- 

 guished, while it is yet little larger than the globules of 

 mucilage, and may be traced onwards uninterruptedly, 

 any deposition of mucilaginous granules upon it being 

 out of the question. On this point I refer to the preced- 

 ing treatise, where it treats of free cell-formation in the 

 embryo-sac.* The origin of the nuclei free in the cell- 

 contents consequently affords no evidence in favour of 

 the assumption, that they are solid granules without a 

 membrane. 



Schleiden says moreover, that " in young free cytoblasts 

 no trace of a membrane is found." The youngest nuclei 

 consist of a homogeneous substance. They are either 

 more dense than the surrounding fluid, or, as is frequently 

 the case in young parenchyma-cells, they are less dense 

 than the surrounding mucilaginous contents, and appear 

 like hollow spaces in it. In this youngest condition 

 examination certainly reveals no membrane distinguish- 

 able from the contents ; but this is not a circumstance 

 which can be of weight in judgment of the nature of the 

 nucleus. If optical instruments never become improved 



used nuclear utricle (kern-bldscheti}, as synonymous with nucleus. I still 

 know of no better terminology to substitute for it. On the one side, the 

 analogy with the other kinds of utricle requires the name "nuclear utricle ;" 

 on the other hand, custom of language, brevity of expression, and the con- 

 trast with nucleolus, leads to the use of the term " nucleus." The confusion 

 of language is always greatest when conceptions are in process of discrimi- 

 nation. Selecting from a hundred examples in botany, does not the same 

 author use spiral vessel and spiral-fibrous cell, or liber-fibre and liber-cell as 

 synonymous, although in regard to the last example, the \vord fibre already 

 represents a perfectly definite conception. 

 * See page 103 of this volume. 



