. Chemical embryology. Embryology. SECT. 2] AND WEIGHT 401 Davs Mitotic period in calculatec development index hours minutes 38 minu 2 22-5 19 42 — 3 21-2 20 55 — 5 169 26 11 15-7 7 150 29 24 94 9 8-3 53 II IO-2 II lO-O 44 3 4-8 13 7-0 70 15 57 15 4-4 100 33 40 17 3-7 117 39 2-5 19 2-8 155 55 4-2 21 1-2 363 7 1-8 10 (after hatching) 00 — The fall in the mitotic index ran closely parallel with the fall in the percentage growth-rate of the organ, as determined by a special series of weighings. The time taken by one mitosis was calculated from these data by Olivo & Slavich: it turned out to b
. Chemical embryology. Embryology. SECT. 2] AND WEIGHT 401 Davs Mitotic period in calculatec development index hours minutes 38 minu 2 22-5 19 42 — 3 21-2 20 55 — 5 169 26 11 15-7 7 150 29 24 94 9 8-3 53 II IO-2 II lO-O 44 3 4-8 13 7-0 70 15 57 15 4-4 100 33 40 17 3-7 117 39 2-5 19 2-8 155 55 4-2 21 1-2 363 7 1-8 10 (after hatching) 00 — The fall in the mitotic index ran closely parallel with the fall in the percentage growth-rate of the organ, as determined by a special series of weighings. The time taken by one mitosis was calculated from these data by Olivo & Slavich: it turned out to be constant at 38 minutes. But the intermitotic period grew longer and longer, indicating that the later growth consists less than the former of proliferation and more of increase in size of the cells already formed. o o\. ( Males ] Z 5 811 17 23 29 3S3« 45 75 80 105 120 135 150 165 180 185 210 dstye 241 Fig- 43- For a long time Minot's way of looking at embryonic growth in par- ticular and growth in general was universally adopted, by Jenkinson, and even at the present time it is much used. But the Minot curve is undoubtedly based on a fallacy, and it was not long before a feeling that this was so began to arise. It was perhaps intensified by the appearance of such estimates as that of Muhlmann, who worked out the growth-rates in early stages of N E I . 26. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Needham, Joseph, 1900-. New York: The MacMillan Co.
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