Abstract
In an endeavor to test the claims of Soli 1 that extirpation of the thymus gland of the laying fowl leads to the total temporary suppression of shells on eggs laid subsequently, this gland was removed from 3 one-year-old, actively laying, pure-bred Brown Leghorn hens which had been carefully trap-nested since the onset of the laying period. All 3 birds laid in the morning of the day their thymus glands were removed. Recovery was uneventful but the immediate effect was a temporary cessation of egg laying. One bird (No. 29) recommenced laying 10 days later while the other 2 (Nos. 39 and 94) started again 15 days after the operation. All laid regularly thereafter until killed 8 to 9 weeks later.
The eggs laid in the postoperative period were, with one exception, normal in respect to size and shell thickness. The one exception was provided by No. 29 which laid a small egg 61 days after the date of operation. Since this bird produced 2 small eggs within a few weeks immediately preceding the removal of the thymus the small egg subsequently laid is not definitely attributable to the effect of the removal of the gland.
Soli reported that 15 or 20 days following this operation the fowl's calcium metabolism becomes deranged, and that this was indicated by the production of eggs in which the shell was either totally or partially suppressed; after another short period (at about 40 days) there was a return to a normal calcium metabolism and the production of eggs with normal shells.
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