In​ ​the​ ​presence​ ​of​ ​a​ ​lipid-rich​ ​solution​ ​and​…

In​ ​the​ ​presence​ ​of​ ​a​ ​lipid-rich​ ​solution​ ​and​ ​water, ​ ​_______________ ​forms​ ​a distinct​ ​layer​ ​or​ ​clump​ ​in​ ​the​ ​ ​test​ ​tube.