Prankerd .— Notes on the Occurrence of Multinucleate Cells. 603 
not immediately after direct division of the nuclei. In several different 
plants, which show binucleate cells, I have observed two nucleated proto¬ 
plasts within one cell-wall (Fig. 6, b\ and though this appearance might 
conceivably be due to artefact, comparison with other cells of the tissues in 
which they occur makes it seem probable that this apparent cleavage 
of the protoplasm represents the first stage of wall-formation. 
Finally, it may be noted that multinucleate cells tend to occur in 
regions of activity (cotyledonary nodes of seedlings) and rapid elongation 
(stems of buds). In general, the cells show dense cytoplasm, and the 
nuclei are usually near the centre, possessing one or more large, refringent, 
and deeply staining nucleoli. Considerable plasticity is often shown in the 
size and shape of the nuclei in these tissues (Figs. 2 and 4). Binucleate 
cells in actual meristem occur rarely, if at all; for example, the pith of the 
bud of Mortis nigra , fixed February 5, 1915, showed typical uninucleate 
cells, while the pith towards the apex in opened buds gathered May 9, 
1915, was composed mostly of multinucleate cells. 
If direct nuclear division with subsequent wall-formation does occur, as 
the above observations suggest, the ‘ heretical opinion ’ expressed by Arber 
that c amitosis plays an active part in the growth of the young roots 
of Stratiotes ’ ((1), p. 374) is not only confirmed, but shown to be of far 
wider application. 
Summary. 
1. Multinucleate (usually binucleate) cells occur in different tissues 
of various young organs in a number of plants widely separated both 
as to habit and systematic position, and it is suggested that their occurrence 
is characteristic of regions of active growth. 
2 . In some cases, at least, these nuclei are probably produced by 
amitosis followed by wall-formation, and the view is maintained that these 
processes are a means of tissue-formation in rapidly growing organs. 
Many of the preparations used in the above were made in connexion 
with a research I have been carrying out for some years in Professor 
Oliver’s laboratory, University College, London. Microtome series through 
some grass seedlings were kindly lent me by Miss Sargant and Dr. Agnes 
Arber, and some other preparations by Dr. E. N. Thomas and several 
members of her Department at Bedford College, to all of whom I tender my 
thanks. I am also grateful to Dr. Agnes Arber for the interest she has 
taken in my work, and to my assistant, Miss G. E. M. Piper, B.Sc., for her 
sympathetic help. 
Botanical Research Laboratory, 
Bedford College. 
