Vertebrate embryology : comprising the early history of the embryo and its foetal membranes / by J.W. Jenkinson.

  • Jenkinson, J. W. (John Wilfrid), 1871-1915.
Date:
1913
Catalogue details

Licence: In copyright

Credit: Vertebrate embryology : comprising the early history of the embryo and its foetal membranes / by J.W. Jenkinson. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    A guinea-pig reaches 775 grammes in 432 days. A man ,, 63,000 grammes in 9,428 days. The average percentage increments are Guinea-pig 0 47 grammes. Man 0-02 Fig. 4.—Curve showing the yearly percentage increments in weight of boys. (From Minot, 1907.) In the human being, therefore, growth is much slower than in the guinea-pig, and man is only eventually the bigger of the two because he goes on growing for so much longer. It is of course a commonplace of embryology that the growth of all the organs of the body does not proceed at the same rate. The parts, however, obey the same law of diminishing rate as does the whole. This may be seen in the figure (Fig. 5) in which the changes in the rate of increase of the human being in respect of stature, head-length, length of vertebral column, and length of leg are shown. The progressive loss of growth power is spoken of by Minot as ‘ senescence ’. The same author has brought forward some evidence to show that during differentiation there is an increase