PINE-APPLE——BIENNIAL COURSE. 355 
have denominated the biennial course was first brought into 
notice by Abercrombie, and more recently has been strenu- 
ously recommended by Baldwin. Its chief feature is the 
acceleration of ‘the growth of the plants by the application 
of higher temperatures than it was formerly supposed they 
would flourish in. They are, in fact, made to attain the 
growth of two summers in the course of one year. 
About the beginning of March, the most forward of the 
plants potted over winter, or the suckers kept in tan, are 
taken out, the earth or tan taken away, and the roots 
shortened. They are then put into pots about five inches 
in diameter, which are plunged into frames or pits heated 
with tan or stable- litter. They are shaded as usual, and, 
after they begin to grow, receive moderate waterings. 
When the roots appear around the balls of soil, which will 
be-about the middle of June, the plants are again shifted 
into larger pots, from six to seven inches in diameter, and, 
if the heat be declining, are removed into other pits or 
beds. In the beginning of August they are transferred 
into large pots, in which, unless they are intended for early 
spring forcing, they stand during the winter; and in Feb- 
ruary they are finally shifted into pots twelve or fourteen 
inches in diameter.. For spring forcing, the last shifting 
takes place in October, and the pots may be two inches 
narrower. At every shifting the ball of earth is preserved 
entire. From March the temperature is gradually in- 
creased ; little air is admitted, even in strong sunshine, and 
a lively” thotiom-hent is kept up by means of repeated lin- 
ings. When there is danger of scorching the roots, the 
pots are partially drawn up, or even sect upon the surface 
of the tan.. The’ following table will give an idea of the 
temperature (Fahrenheit’s thermometer) and its progressive 
increase :— 
