16 Transactions of the Society. 



name of '* Polygonum Sieboldii," multinucleate cells were described 

 by Grant.* I can confirm his statement that the ground tissue is 

 multinucleate. I have found binucleate cells both in the pith^ 

 cortex and epidermis of the relatively young internodes ; in the 

 pith they are extremely numerous. But my observations on the 

 origin of these nuclei fail to accord with those of this author. He 

 writes, " In this plant I have been enabled to trace the formation 

 of the multinucleate condition distinctly, and have found it in all 

 cases to be due to * direct division.' " I have observed lobed nuclei 

 similar to those figured by Grant, especially at some little distance 

 from the stem apex, but I regard these as senile phases, or possibly 

 in some cases the results of poor fixation, rather than stages of 

 direct nuclear division. In both pith, cortex and epidermis, 

 especially in the younger internodes, the formation of paired nuclei 

 with associated phragmospheres (PL I, fig. 26) has been observed. 

 Various karyokinetic stages showing the spindle and chromosomes 

 have also been noticed (e.g. the prophase seen in PI. I, fig. 25), and 

 there thus seems no reason to doubt that the binucleate condition 

 originates, as in the other cases studied by Mr. Beer and the 

 present writer, by karyokinesis rather than by the amitosis 

 described by Grant. 



I can confirm Grant's account of the fusiform and sometimes 

 extremely elongated nuclei which occur in the elongated vascular 

 elements. But I have been unable to detect any cases of the 

 multinucleate cells described by this author as occurring in tan- 

 gential sections of the vascular bundles. It seems possible that 

 Grant mistook the nuclei of adjacent elements, of very narrow 

 lumen, for nuclei occurring within the same cell — a mistake which 

 it is exceedingly easy to make in the case of these longitudinal 

 sections. 



Morus nigra L. (PL I, figs. 12 A-C). 



Morus nigra, the Mulberry, is one of the species in which Miss 

 Prankerd f has described and figured the occurrence of multinu- 

 cleate cells in the pith and cortex of the axis. She considers 

 it probable that the presence of more than one nucleus in these 

 cells is due to amitosis. I have re-examined this plant, and am 

 able to confirm the existence of multinucleate cells in the develop- 

 ing axis. I have found definite evidence, however, that the 

 increase in the number of nuclei comes about, as in other cases 

 described in the present paper, by karyokinesis. Young shoots of 

 Mulberry were fixed on May 8, 1916, soon after the buds had 

 expanded ; these were thus probably at a closely similar stage to 

 the material described by Miss Prankerd, which was gathered on 

 May 9, 1915. In both pith and cortex of the young axis spindle 



• Grant, A. E. (1886). f Prankerd, T. L. (1916). 



