TRANSACTIONS OF SECTION K. 677 
which may be expected under the particular conditions under which the 
farmer must work. 
Considering the fact that empirical trials will tend to establish the most 
simple conditions of usefulness, the following lines of investigation were 
cited as most likely to promote a normal and efficiently rapid develop- 
ment of the process: (1) The exact nature of the chemical or chemicals 
employed ; (2) the substances in the weeds and crop plants most likely 
or apt in physical, chemical, or physiological action; (3) the relation of 
the particular reactions as influenced by atmospheric moisture, soil 
moisture, sunlight and heat; (4) the action of the sprays as influenced 
by the chemical type of the soil, and the age of the plants to be treated ; 
(5) the spread of reaction between the cropping plant and the weed 
concerned as evidenced in susceptibility to the sprays, and as shown in 
structural and physiological differences ; (6) the form of spray most suited 
to do the work in each particular case; (7) what organisms are concerned 
other than the cropping plants and the weeds attacked. 
3. Some Effects of Tropical Conditions on the Development of certain 
. English Ginotheras. By Dr. R. R. Gatzs. 
The seeds for these cultures were obtained from near Liverpool, 
England, through the kindness of Dr. D. T. MacDougal, and the first 
culture was planted in the tropical greenhouse at the University of Chicago, 
July 1907. Fifty-six plants were grown in this culture, and soon there 
were seen to be two distinct series of rosettes, one of which proved to be 
derivatives of 0. Lamarckiana’ and the other of O. grandiflora. The former, 
which included just half the culture, produced a variety of forms, including 
types very closely related to the mutants of De Vries, and others quite 
different from them. All but six of these continued in the rosette stage, 
and were still rosettes when the culture was discontinued in May 1909, 
nearly two years after it was begun. 
During the twenty-two months of the culture many of the rosettes 
continued producing cycle after cycle of rosette leaves above, the old leaves 
dying away below. This was accompanied by a great amount of growth 
of the stem in thickness and some growth in length, but no internodes were 
formed. The result was a stem, in one or two cases eight or ten inches high, 
having a striking similarity to the appearance of a cycad, with its surface 
covered with leaf bases and leaf scars arranged in diagonal series and 
surmounted by a crown of rosette leaves. Several plants of this 
O. Lamarckiana series, after producing a considerable leaf-base area, 
finally, in October and November 1908, sent up a stem of the ordinary 
type. These stems showed marked fasciation, and the branches were few, 
irregular, and high up on the stems. The same applies to a less extent 
to the O. grandiflora derivatives. The main stem, particularly when 
fasciated, often drooped over and grew horizontally or downwards for a 
time, later growth being erect again. 
The other half of this culture is of special interest, because I have 
shown them to be derived from O. grandiflora. ‘The rosettes are markedly 
different from those of any of the O. Lamarckiana series. Several types 
of leaves succeed each other as the rosette develops. In the tropical culture, 
in the final rosette stage, the leaves have deep lobes at their base. This 
stage is entirely omitted when the plants are grown under ordinary con- 
ditions, as shown by my cultures this year at the Missouri Botanical 
Gardens, from offspring of the plants in this culture, as well as from seeds 
1 As already known from Charles Bailey, Manchester Mem. 61, No. 11, 1907, and 
MacDougal, Carnegie Pub. No 81, 1907. 
