165 
APPARATUS FOR AHRATING PLANTS. 
b 
BY 
F. M. ANDREWS. 
I have made use of the well known Bunsen pump with some additions 
or modifications for the purpose of aerating water cultures. Sometimes I 
have used it for aerating cultures not grown in water also with good results. 
In a previous papert I have shown the advantageous effect that the 
passing of air through a water culture has on the plant. A like bene- 
ficial effect was also found when air was passed through soil in which the 
corn plant was growing. In the paper just referred to the Kekulé apparatus 
as described by Ostwald was also used for some experiments with equally 
favorable results. Of the Kukulé and Bunsen apparatus for the purpose of 
aerating the latter, as I arranged it, will furnish by far the greater amount 
of air to be passed through a culture. So far as convenience is concerned, 
however, in other respects there is the further advantage of the Bunsen 
‘apparatus in that much less space is required to operate it. The perpen- 
dicular tube which conveys the chain of bubbles of air and water down- 
ward must be of such a length that the sum of the lengths of the short 
columns of water in this perpendicular tube between the columns of air 
will more than equal the depth of the solution through which the air is to 
be passed. This necessitates a perpendicular tube of considerable length. 
In the Kukulé apparatus I used the perpendicular tube has a length of 120 
em. while the culture solution had a depth of only 20 em. Of course the 
length of the perpendicular tube and the speed with which the chain of 
air and water will pass through it can be made to depend somewhat on the 
length of the single columns of water for sometimes these columns of water 
are short and sometimes long depending on the quantity of water which 
enters the tube in the form of individual drops. Another drawback to 
the Kekulé’s apparatus is that the perpendicular tube is often rapidly 
clogged completely with algae of various kinds, mostly those belonging 
to the Cyanophyceae, and with iron deposits as well as some sediment. 
In the Proceedings of the Indiana Academy of Science for 1916 Mr. C. C. 
Beals’, who carried out a piece of work on aeration under my direction, 
has shown a brief sketch of the Kekulé apparatus. At b in his diagram 
he shows the perpendicular tube in question. In order to form bubbles 
readily this tube as arranged should not be over 4 mm. in diameter. This 
smallness of size of the tube, however, contributes to the accumulation and 
stoppage of the tube. The algae as well as the iron can be quickly cleaned 
out of the tube by using 50% or 60% HCl. Weaker strengths as 10% and 
15% HCl were tried at first to clean the tube but they were not effective. 
Experiments are in progress to try to prevent this troublesome phase of 
the accumulation of material in the tube. Its stoppage often occurred in a 
few days; at other times in two weeks. This necessitated the disconnecting 
1The Effect of Soaking in Water and of Aeration on the Growth of Zea Mays. 
Bulletin of the Torrey Botanical Club, 1919, Vol. 46, PP. 94-100. 
1Beals, C. C.—The effect of Aeration on the Roots of Zea Mays. Proc. nd. Acad. 
of Science. 1916, P. 177. 
