Notes. 
569 
It may be suggested here that the most satisfactory homology of the parts 
of the perithecium in Sphaerotheca is to regard the oogonium as a uninucleate 
ascogonium, which, after fertilization, develops directly by division into a row 
of cells, i. e. into a single ascogenous hypha , of which the usual penultimate cell 
becomes the ascus. This row of cells cannot satisfactorily be compared with 
the whole ‘ scolecite * of Ascobolus , for that is certainly not, itself, a product of 
fertilization. 
V. H. BLACKMAN. 
H. C. I. FRASER. 
London. 
THE POSITION OF MAXIMUM GEOTROPIC STIMULATION.— In a recent 
paper in which he discusses the position of maximum geotropic stimulation, Fitting 1 
refers to a note by me published in this Journal in 1899 2 . I then obtained 
results with apogeotropic organs which seemed to prove that the optimum position 
lay at 45 0 below the horizontal, but experiments of the same kind and others 
which are still more conclusive, carried out by Fitting, all indicate that the horizontal 
is the optimum position. Fitting suggests that the difference in my results is 
possibly due to a slight deviation from the horizontal in the position of the axis 
of my klinostat, which error would, as he proves experimentally, be quite sufficient 
to account for my results. 
Although Fitting's experiments are so convincing as to leave little doubt that 
the error must lie with me, it yet seemed desirable to repeat my experiments. 
I again made use of grass-haulms (those of Lolium perenne) and fixed them 
on an intermittent klinostat at an angle of 45 0 to the horizontal axis (the position 
of which was most carefully adjusted) so that they were for periods of 25 minutes 
alternately 45 0 above and below the horizontal. The results, unlike those of my 
earlier experiments, quite agreed with those of Fitting, for there was no indication 
of any difference in the amount of stimulation in the two positions. Of twenty-eight 
grass-haulms ten remained straight; eleven curved towards the horizontal with an 
average curve of 6-i°, and seven curved in the opposite direction with an average 
curve of 11-7°. The experiments, five in number, were all carried on for about 
twenty-three hours. 
In order to obtain more positive results I then employed a method suggested 
and carried out by Fitting. Inclining the axis of the klinostat 22^5° from the 
horizontal, I so arranged the haulms that they were alternately horizontal and 45 0 
below the horizontal. Almost without exception they curved decidedly away from 
the side which was stimulated whilst horizontal, showing that the stimulus in 
that position is greater than it is when inclined 45° below the horizontal. Of 
1 Untersuchungen iiber den geotropischen Reizvorgang, Teil I. Jahrb. fur wiss. Bot. xli. 2. 
1905. See also F. C. Newcombe, Geotropic responses at various angles of inclination. Ann. of 
Botany, 1905, p. 319. 
2 On the gravitation stimulus in relation to position. Ann. of Botany, 1899, p. 620. 
