MUTATIONS, VARIATIONS, AND RELATIONs - SCOPE OF INVESTIGATION. - The oenotheras have furnished so much evidence of importance in connec- tion with saltatory action in heredity that it has been deemed important to continue the cultural investigation of the group begun in 1902. Seeds representing the species in cultivation in the principal botanical gardensof the world have been procured, and these, in addition to a large num- ber of forms native to eastern North America, have been grown in guarded cultures. Attention has been paid to the occurrence of mutants in Oemthera lamarck- iana with a view to testing the coefficient of mutability and the influence of environmental conditions on mutation. Extensive sowings have been made for the purpose of finding derivatives hitherto undetected, with a coefficient of mutability so small as to have escaped observation. Descriptions of known mutants have been made independently for the purpose of comparison with supposedly identical forms in Amsterdam and of facilitating observations of all kinds upon the subject. Many important relations between mutants and their parents may be riost advantageously considered by statistical methods, and the studies begun by one of the authors in 1904 have been continued and extended to include addi- tional mutants. The height and branching of the stems and the width and length of the leaves have been again taken into account, but owing to the great susceptibility of these organs to variation in direct response to environ- ment, measurements have also been made upon the buds. The lesser varia- tion of the latter in correlation with vegetative characters makes them much more satisfactory for the study of hereditary relations, and it is clear that their statistical study in connection with pedigree-cultures will demonstrate in several generations the permanence or evanescence of the mutant types and give decisive answers to such questions as the relation between fluctua- tion and mutation and the fixing of variations through self-fertilizations or their disappearance through crossings. Guarded p-digree-cultures have been made from pure seeds of native species of evening-primroses which had not previously been brought under close observation, with a view to procuring additional evidence on mutability in this group. The preliminary examination made it apparent that the group comprises a swarm of clearly separable species, many of which had not been recognized by the taxonomists and which gave basis for the current opinion as to the wide variability of the common evening-primrose 0. biennis. The study of genetic relationships and of the phenomena of hybridization in general has necessitated the organization of extensive cultures, which will need continuance for two or more seasons before definite results may be announced, and their discussion is reserved for a future paper. A few cases of fixed hybrids have been encountered, however, in which the crossing of two species resulted in the production of a progeny consisting of one fixed type constant in successive generations. Forms arising in this way are, in reality, new species, and doubtless many such have arisen naturally and now constitute a part of the native flora. Striking cases of vegetative mutation, or bud-sports, having arisen, atten- tion has bcen devoted to a study of the inheritance of the saltatory groups of characters...