The data give the numbers of rotifers falling out of suspension for
different fluid densities. There are two species, `pm`

*Polyartha major* and `kc`

, *Keratella cochlearis* and
for each species the number falling out and the total number are
given.

`rotifer`

`density`

specific density of fluid.

`pm.y`

number falling out for

*P. major*.`pm.total`

total number of

*P. major*.`kc.y`

number falling out for

*K. cochlearis*.`kc.tot`

total number of

*K. cochlearis*.