28 Transactions of the Society. 



Simultaneously with McLean's paper one of us (Arber, A., 1914} 

 described multinucleate cells and lobed nuclei in Stratiotes aloides. 

 The root-cap of a young adventitious root, and certain cells of the 

 stem cortex through which it was dissolving its way, were observed 

 in some instances to be highly multinucleate, as many as twelve 

 nuclei being observed in one case in a single cell of the root-cap, 

 Lobed nuclei are notably frequent in the conjunctive tissue of the 

 stele. Further work on Stratiotes has convinced us that the 

 conclusions expressed in this paper as to the part played by 

 amitosis require revision ; we have now observed the origin of the 

 binucleate condition through karyokinesis, and we regard the 

 lobing, which was formerly supposed to be a precursor of amitosis, 

 as having no connexion with any division.* 



A year later than the appearance of the two papers which we 

 have just considered, Miss Prankerd (1915) published an account 

 of her researches on multinucleate cells. She recorded the 

 occurrence of elements with more than one nucleus in thirty-six 

 species of plants " widely separated in habit, habitat, and systematic 

 position," including both Vascular Cryptogams and Angiosperms. 

 The plurality of nuclei was observed sometimes in the pith, 

 sometimes in the cortex, and sometimes in both tissues. It was 

 also found in the mesophyll of some plumular leaves (e.g. Zizania 

 aquatica) and in the ground tissue of certain Ferns and 

 Monocotyledons. Binucleate cells were usually found, but in 

 certain cases (e.g. Armn maculatifjii, Limnanthcmuni jpeltatiim, 

 Zizania aquatica and Morus nigra) three or even more nuclei 

 could be observed in some of the cells. It was found that the 

 multinucleate elements tend to occur in regions of activity 

 (cotyledonary nodes of seedlings) and of rapid elongation (axes of 

 buds). Miss Prankerd considers that, in general, the plurality of 

 nuclei arises by amitosis. We have re-examined certain of the 

 species with which Miss Prankerd's studies were concerned, and 

 again — as in the case of Grant's and McLean's work — we find that 

 we can confirm the existence of the multinucleate phase, but that 

 our observations point entirely to mitosis, and not direct division, 

 as the mode of origin of the extra nuclei. t 



In the same issue of the Annals of Botany as that in which 

 Miss Prankerd's paper appeared, we published a preliminary note 

 dealing with the same subject (Beer, R. and Arber, A., 1915). We 

 recorded a plurality of nuclei in the young parenchymatous tissues 

 of seventy-six species, chiefly Angiosperms, but including also a 

 Gymuosperm and a Vascular Cryptogam. This phenomenon 

 seemed to us so widespread that we suggested the possibility that 

 a binucleate or multinucleate stage might often intervene as a 

 normal phase of development between the meristematic and adult 



* Arler, A. (1920). t Ibid. 



