The percentage of clover plants surviving from treatments on the chlorate-treated soil where both inoculation and ammonium sulfate were used was still significantly lower than the percentage survival of plants growing in the untreated check soil. Inoculation of the clover seed, the application of ammonium sulfate, and a combination of the two increased the survival of clover plants on the chlorate-treated soil. Inoculation increased the survival of clover plants on the untreated soil. Ammonium sulfate gave the least increase in percentage survival of the clover plants growing in the chlorate-treated soil, but the increase was quite significant. Inoculation of the seed was next, with the combined treatment giving the largest increase. In the case of plants growing in the chlorate-treated soil, there was a correlation of .65 +/- .04 between the percentage of plants surviving from a treatment and the average nodules per plant on the plants which survived from that treatment. No data were available for similar tests under field conditions. The writer believes that such field tests would be desirable as these experiments indicated that it may be possible by such means to grow crops on small areas which have received applications of chlorate much sooner than could be done otherwise. It would be desirable to test different amounts and types of nitrogen fertilizers, using several common field crops.

1 The dental peculiarities of the walrus, Odobenus obesus, may be ascribed in their entirety to the structural modifications induced by the huge size of the canine tusks and to the diet which the animal has adopted. 2 The dental succession is best represented by the formulæ: Deciduous i. 3/3, c. 1/1, m. 3/3 = 28; Successional I. 2/0, C. 1/1, P. 4/3, M. 1/1 = 26; Functional I. 1/0, C. 1/1, P. 3/3 = 18. The last of these is well known. The first differs from previous interpretations in recognizing but three milk‐molars, and the second is devised to acknowledge definitely the existence of a successional upper second incisor and fourth premolar and to designate as true molars the upper and lower posterior rudimentary teeth. 3 The enlargement of the upper canines has caused the loss of the medial incisors, the alignment of the outer upper incisor and lower canine with the cheek‐teeth, and an antero‐lateral shift in the angle of implantation of the upper teeth. 4 The diet, composed chiefly of hard‐shelled molluscs, has required a concentration of force in the anterior portion of the mouth. This has been accomplished by the production of massive jaw‐bones and heavy solid dental columns. 5 The necessity for an adequate dental armament at an early age has been met (a) by a long period of suckling, while the face and teeth were growing; (b) by the nearly simultaneous eruption of the entire dental battery; and (c) by the expanding cones of the growing roots, which made it possible for dental equipment to keep pace with facial development without additional teeth, a mechanism not noted in any other mammal. 6 The details of the processes of structural modification, growth, wear, and senescence related to the dentition have been recited according to the evidence available. 7 By the application of the principles set forth in this discussion miscellaneous specimens of teeth may be identified with reasonable accuracy.

This paper describes the morphological changes of the gut of Vespa during metamorphosis, and also the histological changes which occur in the mid‐gut epithelium. The first histological changes are observed in the late larval stage (pre‐pupa), when phenomena of disputed significance occur—the formation of globules and their apparent liberation into the gut‐lumen This is followed by rapid multiplication of the replacement‐cells. The bases of the histolyzing epithelial cells contain large vacuoles, and it is probable that these exert a mechanical force, pushing the epithelium away from the basement‐membrane. This process of casting is probably aided also by chemical disintegration of the cell‐bases and basement‐membrane, by the force exerted by the rapidly growing replacement‐cells, and by severe muscular peristalsis of the intestinal muscle‐layers. The rapid proliferation of the replacement‐cells leads to the formation of the new epithelium. This is at first irregularly disposed and thrown into folds which disappear as the diameter of the gut increases. The cast epithelium lies in the gut‐lumen, and is removed by an undetermined method, probably a combination of “auto‐digestion” and by enzymes liberated from the new cell‐layer. Phagocytosis plays no part in the process. The early epithelium shows certain characteristic features, particularly a refringent edge, which splits away by delamination and gives rise in this manner to the peritrophic membrane which thus arises during the pupal period. There is only one pupal epithelium. The adult morphology is attained before the imago emerges, but the cells of the epithelium are small and “cuboid.” The final histological characters (such as greater size, perinuclear space, etc.), are not at first present, and probably do not appear until after the first meal. A discussion of the time‐relations of these various processes and consideration of the results of other investigations leads to the theory that metamorphosis is started by a single original stimulus, and though some amount of progress may follow from this, its completion appears to depend upon the serial development of other succeeding stimuli each responsible for some particular phase.