The Association of Vitamin a with Greenness in Plant Tissue. Ii. the Vitamin a Content of Asparagus.*

Since previous experiments (1) showed that the vitamin A content of head and leaf lettuce varied more or less directly with the greenness of the plant tissue, investigations in which asparagus was used as the source of this vitamin were undertaken. It was thought that certain questions concerning the vitamin properties of asparagus, which arise from the fact that it is offered for consumption in both the green and bleached state and also as a canned product, might be answered. The experiments have been in progress over a period of 2years (1927-1928), within which time some of the results from the first season’s work have been checked by those of the second. Experimental technique was essentially the same as that employed in the tests with lettuce (1). Albino rats were placed on a vitamin A-free ration, complete in all other dietary essentials, until their store of the vitamin was depleted. Following this, different types and varying amounts of asparagus were fed and growth determined over a period of 8 weeks. The asparagus was of the Martha Washington variety, from plants growing in the college gardens, these plants being several years old, vigorous, and free from disease. Bleached (term used where tissues have never been allowed to become green) tips were secured, in season, by covering over certain rows with about 4 inches of soil and cutting the stalks just before their emergence above the surface of the ground. When freshly cooked tips were