Structure and Division of the Vegetable Cell. 215 



nuclear plate and nuclear spindle is mentioned. In Orni- 

 tJiogalum and Scilla, if such exists, I have not seen it ; in 

 Spirogyra it is certainly wanting. In Equisetum limosum, 

 however, all these phenomenal stages are passed through, 

 and we will now shortly notice tlicm. 



Structure and Division of the Cells of Equisetum limosum, L. 



The study of U. limosum was made from specimens 

 gathered about 11 a.m. in June of last year, and preserved in 

 alcohol. Longitudinal sections were made of young growing- 

 shoots which had just appeared above ground. 



The hypodermal and fundamental cellular tissue round 

 the nodes abounded with dividing cells in all stages, four or 

 six sometimes being in the field at once. The cells of the 

 hypodermal tissue were quite filled with protoplasm, con- 

 taining a nucleus at least half the size of the cell, with 

 nucleolus and nucleolo-nucleus. They were closely packed, 

 and seemed to be multiplying rapidly. On the contrary, the 

 fundamental tissue cells, even at the upper or lower parts of 

 the nodes, were considerably or greatly vacuolated, and had 

 a nucleus not more than one-fourth the size of the cell, with 

 two to four nucleoli. Essentially the same appearances were 

 seen in both kinds at the same stage of division, though in the 

 fundamental tissue-cells certain important steps were traced 

 which were absent from the others. On this account they 

 have been chosen for a short description. The first move- 

 ment that has been noticed is a massing of the nucleoplasm 

 to form a clear, broad, hyaline band across the centre of the 

 nucleus, the poles of which are left as pale conical projec- 

 tions from the sides of the baud (Plate IX. fig. 21). The 

 nucleoplasm thus aggregated is very pellucid aud highly 

 refractive, so much so, contrasted with neighbouring nuclei 

 not dividing, that one can easily, after shifting the prepara- 

 tion under the field, find it again by this property. That it 

 is the surface alone which thus refracts, is proved on attempt- 

 ing to focus so as to examine the contents, the result being 

 that a general glairy indistinctness takes the place of the 

 former brilliance, so that if definable structures were in the 

 interior at this time it is impossible to see them. This 

 pellucid band is Strasburgcr's nuclear 'plate, while the pale 



