Pinus sylvestris. -hybrids of, with P. nigricans.
PIORRY, on hereditary disease.
Pistacia lentiscus.
Pistacia vera.
PISTILS, rudimentary, in cultivated plants.
Pistor, sterility of some mongrel pigeons. -fertility of pigeons.
Pisum arvense and sativum.
PITYRIASIS versicolor, inheritance of.
PLANCHON, G., on a fossil vine. -sterility of Jussiaea grandiflora in France.
PLANE-TREE, variety of the.