. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. COLD-INDUCED ANOMALIES IN T. TOROSUS 3 I am indebted to Dr. Costello for the use of 27 tail-tip preparations of T. torosits larvae, made by him in 1942. These tips were derived from embryos which had been cold-treated 5 to 80 minutes after insemination, for periods of 18 to 23 hours. No preparations from newly regenerated tail-tips of this group were prepared and only first clippings are included in the data. The larvae were raised at laboratory room temperature. The cold treatments did not involve temperature shock, the egg
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. COLD-INDUCED ANOMALIES IN T. TOROSUS 3 I am indebted to Dr. Costello for the use of 27 tail-tip preparations of T. torosits larvae, made by him in 1942. These tips were derived from embryos which had been cold-treated 5 to 80 minutes after insemination, for periods of 18 to 23 hours. No preparations from newly regenerated tail-tips of this group were prepared and only first clippings are included in the data. The larvae were raised at laboratory room temperature. The cold treatments did not involve temperature shock, the eggs having been chilled gradually and allowed to return slowly to room tempera- ture. The tail-tip epithelium was studied at a magnification of 210 X, and any figures ' 't' special interest noted on a small "map" of the tip. Using an oil immersion ob-. i FIGURE 1. A group of T. torosus larvae, cold-treated at the gastrula stage for 2 hours at 0° C.; photographed just before their tail-tips were clipped the first time. All ten individuals are normal in general morphology and pigment pattern, but cytologically abnormal to varying degrees. Magnification: X. jective and 10 X compensating occulars, camera lucida drawings of nuclear size were then made of an area on the dorsal side of each tip, as described by Costello and Henley (1949). Mitotic figures were drawn with the camera lucida at a mag- nification of 2100 X, in order to establish chromosome counts. Three criteria were utilized in classifying the tail-tips: variations in nuclear size or nucleolar number, the presence of abnormal mitotic configurations, and the presence of heteroploid metaphases. The relative value of these criteria has been discussed in the paper of Costello and Henley (1949) ; they conclude that only de- cisive chromosome counts of clear mitotic figures are reliable for a definite diagnosis of chromosomal mosaicism, but point out that nucleolar number and nuclear size. Please note that these im
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
