sentences:  One study of several macrosatellite loci in 63 European Pear ("Pyrus communis" L.) cultivars did not distinguish Max Red Bartlett and Sensation Red Bartlett from the standard Williams, which was expected since the red mutants were derived from the Williams by mutation.Dozens of other cultivars and hybrids have been created from Williams, created for properties like cold resistance, ripening time, skin colouration, and grafting compatibility.Best when picked with the internal pressure of the pear is between and , the pear should still be green and relatively hard when picked.