A Letter of Mr Lister Dated May 21. 1673. in York, Partly Taking Notice of the Foregoing Intimations, Partly Communicating Some Anatomical Observations and Experiments Concerning the Unalterable Character of the Whiteness of the Chyle within the Lacteous Veins; together with Divers Particulars Observed in the Guis, Especially Several Fonts of Worms Found in Them