2 BULLETIN 288, U. S. DEPARTMENT OF AGRICULTURE. 
should prompt individuals and communities interested in keeping 
their cotton seed pure to bring about some form of cooperation 
with ginners to effectively provide against the admixture of varieties 
at the gin. 
THE POSSIBILITY OF MIXING SEED. 
The matter of preserving the purity of cotton varieties has not 
been given attention in the designing of ginning machinery, and the 
different machines and their accessories are installed without refer- 
ence to the amount of seed mixing likely to occur. Since either 
the quantity of seed cotton ginned or the output of baled lint governs 
the profits of the ginner, he usually operates his plant from the 
standpoint of output alone, the seed question being purely secondary 
with him. Consequently there are several stages in the ginning 
process where mixing occurs unless certain precautions are exercised. 
The methods generally employed in the operation of custom gins 
are about as follows: 
A patron's seed cotton is taken up from his wagon by suction and is conveyed by 
the same force through flues to the battery of gins. The manner in which the seed 
cotton is distributed to the different gins, usually two to four in number, and the 
condition in which it enters them vary somewhat with the type of ginning outfit 
used. Usually, however, the distribution is preceded by a certain amount of mechani- 
cal beating and pulling, the purpose of which is to clean the seed cotton as much as 
possible and properly condition it for the actual ginning operation. 
The seed cotton enters each gin through a kind of box called the feed box, or feeder. 
The space between the feeder and the saws, where the actual separation of lint and 
seeds takes place, is inclosed by a concave metal surface, and this inclosure is called 
the roll box. 
Upon entering the roll box the seed cotton falls upon the ribs of the gin breast. 
Here the saws, one of which protrudes between each pair of ribs, catch the lint in their 
rapid, revolving motion, pull it from the seeds, and carry it on their teeth to the 
brushes, which in turn take it off the saws and pass it into the lint flues, through which 
it is conveyed by suction to the press. The seeds, being unable to pass between the 
ribs with the lint, fall back and are diverted by means of an inclosed metal apron into 
the seed conveyor. This conveyor, which usually consists of a screw or a belt in a 
groove or trough arranged directly under the gins, takes the seed either to hoppers, 
from which it may be dumped into the patron's wagon, or to the seed house, from which 
it will later be shipped to the oil mill. 
As the saws tear through the seed cotton first fed into the roll box they give to the 
mass a rotary motion. This revolving mass soon assumes the shape of a roll, which 
gives rise to the n^me "roll box. " 
Gradually most of the lint in the roll is removed, and it becomes more truly a roll of 
seed. The regulated supply of seed cotton subsequently fed into the roll box revolves 
upon the roll, the lint is caught by the saws and carried away, and the seeds remain 
as part of the roll or drop out into the conveyor. Thus, there is a constant exchange of 
seed in the roll. 
Once formed, the roll is seldom removed, but usually is allowed to remain through 
long periods of ginning. The ginner ordinarily tries to avoid having the roll run out or 
dropped, which would necessitate the formation of a new one when the next lot of cot- 
ton is fed to the gin. Sometimes the gins are stopped just before the last seed cotton 
of a patron passes out of the feeders, and the amount remaining is ginned as the first 
part of the next patron's cotton. Usually, however, the gin is run several minutes 
