THAT the central nervous system is involved in feather release has been reported by King (1920), Weaver (1936) and Ostmann (1962). The autonomic nervous system also contributes to feather release (Langley, 1904; Ostmann et al., 1963). The results of administration of various classes of drugs on feather release also indicate that the nervous system is involved in this phenomenon (Sturkie et al., 1958; Klose et al., 1961, 1962; Knapp and Newell, 1961; Huston and May, 1961; Ostmann et al., 1963).

THE effect of drugs on the muscles of the feather follicle has received comparatively little attention. Langley (1904) used atropine, curari, apocodine and adrenalin and observed no effects upon the movements of the feathers. In contrast, nicotine, injected intravenously, resulted in a strong depression of the feathers of the body. A subsequent dose, however, failed to add any further effect upon the feathers. He further reported that strychine, following curari, caused irregular erection and depression of the feathers for one to two minutes.

A SEARCH of the literature reveals very little information on the anatomy of the feather follicle and its immediate surroundings. Most of the information available on this subject is in regard to the muscles which move the feather and was reported in the nineteenth century. The muscles of the feather follicle were first described by Nitsch (1840), who reported that four separate muscles were usually attached to the follicle of each contour feather although sometimes six and more rarely five were present. Seuffert (1862) observed that contour feathers of the trunk region usually had two to four separate muscles. He stated that the muscles were unstriated and attached to the follicle by elastic tendons. These muscles were observed to course from the lower part of one follicle to the upper part of an adjacent follicle. Similar observations were made by Helm (1884).

This bulletin reports on University of Missouri Agricultural Experiment Station research project 292, Poultry Photoperiodicity--P. [2].