3 
, 
extremely high towards the end of March, about 63 atmospheres 
(determined through plasmolysis with 17°/, KNO, (weight mol), 
isotonic coefficient 1.69')) diminishes gradually, with the increase 
of volume, to + 7 atm. in the fully developed cells. The length of 
the cells used for our experiments varies from 15 to 25 mm.; the 
osmotic pressure from 13 to 16 atm. 
The starch, when being consumed for the formation of cell-walls, 
is converted into sugars; a sngar (probably glucose) reducing a 
Frarine’s solution, was demonstrable in the young, in the growing 
cells and to a smaller quantity also in the fully developed cells. 
This growth of cells does not occur simultaneously in all places; 
it begins and ends first in the middle parts; in the apical and especially 
in the basal part, enclosed by the calyptra, the growth continues 
longest; finally the length of the cells is nearly the same every- 
where. We subjoin an instance (the measurements were marked 
with Indian ink). 
24 March at 5S a.m. 1 PP ORS Dia 2 Total 10 m.m. 
25 ns 7 B Order akon o. & 5, fe 
26 de x 4 Secon OF Como ao. O SF fale is rn 
21. Ep a paella O0 54 6 8 KR DO ken 
28 pe Be an TORO Ow 020 09 Zee Oe Me 
These values point to a not markedly pronounced large period in 
the total growth; the figures expressing the growth per hour also 
depend, however, on temperature and light. The slightly higher 
day-temperature (= 11°—14° C., room facing the North) acceler- 
ated the growth. Calculated per 12 hrs the successive values for 
another object are: 
det day 2; 1° night 4; 2nd day 6; Zed night 6; oa? day 11, 3rd 
night 10; 4% day 14; 4" night 9; 5 day 5 mm. 
Light also exerts an influence; in the dark the stems become on 
an average 1—2 cm. longer than by daylight, which is chiefly 
attributable to a prolongation of the growth; light, then, shortens 
the grand period. *) 
The average daily increments of 6 specimens were in the dark: 
2 oe A 93, mim. san thes loht: 3,8, 10; 15, 12,:2 mm., 
the circumstances being, for the rest, approximately the same; the 
1st 59 mm. in 7, the 2»¢ 50 mm. in 6 days. 
1) H. Firtine, Jahrb. f. Wiss. Bot. 1919. 
The decrease of the length is only slight in the plasmolytic solution; the cor- 
rection for it may be neglected. 
2) Cf. H. Siere, Biol. Zentralblatt 1920, also J. H. v. BurKom Thesis Utrecht 1913. 
1* 
