STUDIES OF THE MITOTIC FIGURE III. CHAITOPTERUS: CENTRAL BODY STRUCTURE AT METAPHASE, FIRST CLEAVAGE, AFTER USING DILUTED FIXATIVES.

A previous investigation of central bodies in the eggs of Chxtop terus pergamentaceus, at metaphase, first cleavage, described the effects upon their structure of using various modifications of Boveri's picro acetic reagent. It was found that central body configuration is closely related to the coarseness and shape of the astral rays, and that centri oles are demonstrated only when rays are very coarse and undulating (almost straight); this occurs only if the reagent is diluted with about 90 parts of water (Fry, 1932). Since such behavior of central bodies has not been reported elsewhere, and since those of Chxtopterus have heretofore been regarded as typical centrioles, giving genetic continuity to successive division figures (Mead, 1898 and Wilson, 1930), it was thought desirable to determine whether or not the results produced by modifying a picro-acetic mixture hold true when diverse reagents are employed.' II. METHODS For the most part, the methods of the present investigation were the same as those of the earlier study. The eggs used were taken from many females, obtained at different times in the season during the past four summers, at the Marine Biological Laboratory at Woods Hole; they were handled as previously described. As before, eggs of the various sets were left in the reagents from 6 to 15 hours (it was previously shown that these differences do not affect astral types when Boveri's picro-acetic reagent is used, and it is assumed that the sam