THE DISTRIBUTION OF MINERAL MATERIAL IN THE CALCIFIED CARAPACE AND CLAW SHELL OF THE AMERICAN LOBSTER, HOMARUS AMERICANUS, EVALUATED BY MEANS OF MICROROENTGENOGRAMS ,

Abstract

1. Visible light microscopy, microroentgenography, and radioautography were employed as techniques in the qualitative evaluation of the comparative distribution of mineral in the exoskeletons of lobsters and the relative exchangeability of calcium ions in the carapace and claw shells with the surrounding aqueous medium. 2. The following conclusions can be drawn from an examination of photographs obtained using these techniques: (1) In the claw and the carapace, a greater uptake of radiocalcium is observed in the outer portion of the shell. Radioactivity appears to be more uniformly distributed in the outer layer of the claw than in the same region in the carapace. (2) The outer third of the pigmented layer in the claw and the carapace contains the mineral material of greatest density. (3) In the claw, increased mineralization is observed in regions immediately surrounding the tegumental gland ducts and the hair pores; this increased mineralization is not observed in the carapace sections. The laminar nature of the principal calcified zone, observed in microroentgenograms of claw sections, is suggested only in carapace sections 50 microns in thickness. (4) The laminar nature of the pigmented layer of the carapace is obvious in microroentgenograms of cross-sections 50 microns in thickness.