On the Occurrence of Binucleate and Multinucleate 
Cells in Growing Tissues. 
BY 
RUDOLF BEER 
AND 
AGNES ARBER. 
CONSIDERABLE literature exists concerning multinucleate cells 
l\ in the higher plants, tending to show that such cells are far from 
rare. For some time we have been making a study of the subject, at 
first independently and more recently conjointly. Our observations have 
led us to the conclusion that, in the case of the cortical and medullary 
parenchyma of stems, a stage in which each cell characteristically con¬ 
tains more than one nucleus often intervenes as a normal phase of develop¬ 
ment between the meristematic and mature conditions. This stage may 
be highly protracted, or it may be so brief that it is easily overlooked. 
It is most usual to find two nuclei, but the number may be much higher 
in certain species. We have not yet satisfied ourselves as to the fate of 
these nuclei, but there are indications that, at least in some cases, fusions 
occur at a later stage. 
Our present observations would not justify us in saying that the 
binucleate or multinucleate phase is universal, but we have found it so 
widely that we should not be surprised if it eventually proved to be the 
rule rather than the exception. Our preliminary investigation has estab¬ 
lished the existence of a binucleate or multinucleate phase, of greater 
or less completeness, in the stem organs of fifty species of Dicotyledons 
belonging to twenty-seven natural orders and of seventeen species of Mono¬ 
cotyledons belonging to four orders. These cases range from trees to small 
annual herbs and include examples both of vegetative and reproductive 
axes. We have at present given most of our attention to stems, but 
we have also noticed multinucleate cells in the leaf-sheaths of seven species 
of Gramineae 1 and one species of Araceae, and binucleate cells in the 
1 Multinucleate cells in the stems and leaf-sheaths of grasses were recorded by one of us in 
1899. Beer, R. : On the Multinuclear Cells of some Grasses. Natural Science, vol. xv, pp. 434-9, 
2 pi., 1899. 
[Annals of Botany, Vol. XXIX. No. CXVI. October, 1915.] 
