21 
Soil and chlorotic plants were secured from Luquillo (see p. 9). 
The soil was placed in pots and well fertflized. Five chlorotic plants 
were placed in the original soil; these remained chlorotic with very 
little growth. Five chlorotic plants placed in a river sand devoid of 
calcium carbonate became green and made a good growth. Five 
healthy slips placed in the Luquillo soil grew well for a time and then 
became chlorotic. 
Chlorotic plants were also secured from the plantation of Messrs. 
De Sola and Wolff (see p. 15). These on being placed in pots of the 
river sand became green and grew normally. 
These three preliminary experiments showed plainly that the chlo- 
rosis is induced by an unsuitable soil condition, probably the presence 
of too much carbonate of lime. 
Sandy soil was then secured from a plantation near Mayaguez 
where pineapples were growing well. The soil is No. 232 (see p. 15). 
Carbonate of lime in the form of ground sea shells was added to this 
soil in such amounts that different pots contained 5, 10, 13, and 17 
per cent of calcium carbonate. Five equal Red Spanish slips were 
planted. The check plant in the soil containing no calcium carbonate 
remained green throughout the experiment, while all the other plants 
became chlorotic, the chlorosis appearing first and being most intense 
in those pots containing the greatest amount of lime. 
Experiments were then made on a larger scale to see if the addition 
of calcium carbonate to a soil would cause it to produce chlorotic 
plants. The details of the experiments follow. 
The plants were grown in pots that contained 40 pounds of moisture- 
free soil. These were exposed in the open on tables that were pro- 
tected from ants and mealy bugs. Water was supplied only a few 
times in the course of the experiment, as the rainfall was sufficient 
to maintain a good supply of moisture during the period. The size 
of the pots and the frequent rains prevented any appreciable varia- 
tions occurring in the water content of individual pots due to dif- 
ferences in the transpiration of the plants. In each pot only one 
plant was grown, so that practically as much soil was at the disposal 
of the plant as under field conditions. The experiments were run in 
series of five, that is, m every case there were five pots receiving the 
same treatment. 
The pots were planted with suckers obtained from healthy plants 
grown on the station. Previous to planting, all slips were fumigated 
with hydrocyanic-acid gas to kill any mealy bugs or other pests. 
Five different sizes of slips, varying from 6 to 14 inches in length, 
were used in each lot of five pots, but the slips in each lot of five were 
equal to those of every other lot of five. Slips of different sizes were 
used for the purpose of seeing whether the appearance of the chlorosis 
was affected by the initial vigor of the slip. 
[Bull. 11] 
