6 Transactions of the Society. 



result of the examination of the nuclei in these zones, whose 

 growth-history was known. Sections were cut from two regions of 

 an inflorescence axis gathered on May 28th, one of which had not 

 increased in length at all, while the other showed the greatest 

 increase observed in any zone in this particular week — namely, an 

 elongation of from 2*8 to 5*5 cms., or nearly 100 p.c* It was 

 found that in both these cases the nuclei showed the same 

 characteristics ; most of the cells were uninucleate and many of 

 the nuclei were bilobed. In general, the conclusion to be drawn 

 from the different inflorescences which came under observation 

 seems to be that the binucleate stage in which phragmospheres are: 

 abundant is characteristic of the inflorescence in its younger state,, 

 while the period of greatest elongation, which occurs subsequently^ 

 is marked by the presence of single nuclei, Often much lobed and 

 flattened, whose appearance suggests senility. These nuclei seem 

 to remain in much the same condition after the cessation of 

 growth. 



Besides the inflorescence axes, very young leaves gathered in 

 February were examined. They showed binucleate cells and 

 phragmospheres in the mesophyll of their basal centimetre, while- 

 near the apex few nuclei were visible at all, and binucleate cell& 

 were apparently absent. The results obtained from the leaf thus 

 harmonized with those just recorded for the inflorescence, bearing: 

 in mind. that the basal region, in the leaves of this type among the 

 Liliacese, is the growing zone. 



2. Asparagus officinalis L. (PI. I, figs. 13, 27, 28). 



The young shoots of Asparagus, examined in the early part of 

 May, at the stage at which they are usually cut for market, show 

 the binucleate phase very clearly. Sections across the " head " 

 reveal the -presence of binucleate and sometimes trinucleate or 

 even quadrinucleate parenchyma cells in the pith, in the ground 

 tissue between the scattered bundles, and in the cortex.t Binu- 

 cleate cells may also be observed, though rarely, in the xylem 

 parenchyma bordering the young vessels, and in the epidermis. The 

 paired nuclei arise by karyokinesis, the process of division and the 

 formation of phragmospheres occurring precisely as described for 

 the case of Eremurns. Asparagus is less well adapted than Eremurus 

 for the study of the various stages leading up to phragmosphere 

 formation, because, side by side with the production of binucleate 

 cells, wall formation is going on on a considerable scale, in planes 

 both parallel and perpendicular to the axis. The result is that it 



♦ These measurements are only approximately accurate, since the growth of 

 the axis had stretched and blurred the indian ink marks, 

 t Beer, R. and Arber, A. (1919), Text-figs. 1 and 2, p. 9. 



