E. Nettleship to K. Pearson, 22nd Aug. 1908.- External URL
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Sent From (Definite): Edward NettleshipSent To (Definite): Karl PearsonDate: 22 Aug 1908
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Holder (Definite): University College London: Special Collections
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Sent fromEdward Nettleship
22 Aug 1908
Description:
[re: doubts re: P’s rejection of Mendelism – poss. that ratios re: specific character can change over time]
‘...
Another think I cannot quite swallow is that the single brood is comparable with successive single births. I suppose this is based on [the] assumption that germ-cells & sperm-cells once formed are not affected by environment, & on this knowledge (is that conclusive & final]?]) that the total supply of germ- & sperm-cells of each individual is laid down in fo[e]tal life or very early. It is, in regard to influence of environment difficult to form a picture of any process by which a defective organ, & much more a defect of a small part of an organ, in a parent, can influence the (hypothetical) germinal or seminal representative of that organ or part of organ in such a way as to make it produce its own precisely defined defect. But this is no more difficult to understand than how the normal part from a normal organ is produced from its representative in the germ of a sperm. One is much tempted to believe less in the microcosmic representation of every part in the germ or sperm, than in the representation of departments or basal structures or groups of structure i.e. the larger the unit the less difficult the eventual picture becomes. You have spoken somewhat in this sense in your Polydactyly[?] paper (by the way are there not some little printers errors of numbers there?), & Manz[?] speaks somewhat I think in something the same sense. An inheritance of defect of a given system e.g. of the fibrous tissue or the epithelial, or neuro-epithelial &c. &c. [sic] At any rate it seems to me this is worth holding in view. – It would allow an explanation of “equivalent” or “substitution” heredities such as Retinitis pigmentosa (? due to small arteries of choroid nourish the end-organs of the retina) which has as equivalent heredities Deafmutism [sic] (? pathological anatomy) & forms of idiocy & mental defect (? small arteries in pia mater). It might explain what I think we meet with, viz. families in which various eye-“weaknesses” occur, sometimes one kind sometimes another (I am not prepared with data!), whilst it would not be inconsistent with exactly & minutely similar inheritance when this occurs. Perhaps I ought not to bother you with this stuff in the circumstances: you need not reply unless you like: the mere writing out does one some good.
Yrs E. Nettleship.’
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Sent toKarl Pearson
22 Aug 1908
Description:
[re: doubts re: P’s rejection of Mendelism – poss. that ratios re: specific character can change over time]
‘...
Another think I cannot quite swallow is that the single brood is comparable with successive single births. I suppose this is based on [the] assumption that germ-cells & sperm-cells once formed are not affected by environment, & on this knowledge (is that conclusive & final]?]) that the total supply of germ- & sperm-cells of each individual is laid down in fo[e]tal life or very early. It is, in regard to influence of environment difficult to form a picture of any process by which a defective organ, & much more a defect of a small part of an organ, in a parent, can influence the (hypothetical) germinal or seminal representative of that organ or part of organ in such a way as to make it produce its own precisely defined defect. But this is no more difficult to understand than how the normal part from a normal organ is produced from its representative in the germ of a sperm. One is much tempted to believe less in the microcosmic representation of every part in the germ or sperm, than in the representation of departments or basal structures or groups of structure i.e. the larger the unit the less difficult the eventual picture becomes. You have spoken somewhat in this sense in your Polydactyly[?] paper (by the way are there not some little printers errors of numbers there?), & Manz[?] speaks somewhat I think in something the same sense. An inheritance of defect of a given system e.g. of the fibrous tissue or the epithelial, or neuro-epithelial &c. &c. [sic] At any rate it seems to me this is worth holding in view. – It would allow an explanation of “equivalent” or “substitution” heredities such as Retinitis pigmentosa (? due to small arteries of choroid nourish the end-organs of the retina) which has as equivalent heredities Deafmutism [sic] (? pathological anatomy) & forms of idiocy & mental defect (? small arteries in pia mater). It might explain what I think we meet with, viz. families in which various eye-“weaknesses” occur, sometimes one kind sometimes another (I am not prepared with data!), whilst it would not be inconsistent with exactly & minutely similar inheritance when this occurs. Perhaps I ought not to bother you with this stuff in the circumstances: you need not reply unless you like: the mere writing out does one some good.
Yrs E. Nettleship.’
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