LEEUWENHOEK 213 



A countryman of Leeuwenhoek, Antony van Heide, 

 who practised medicine at Middleburg, had several years 

 before this written an account of the anatomy of the 

 mussel,^ which we might have expected to be quoted in 

 this letter ; it was valued by Martin Lister and others. 

 Heide described the crystalline style and the foot, and 

 believed himself to have discovered the " motus miran- 

 dus" (ciliary motion) in the gill of the mussel, but 

 Leeuwenhoek's description of the cilia of the beard of 

 the oyster is a year or two earlier (see p. 212). 



Anodon Embryos^ 



Among the many objects which engaged the attention 

 of Leeuwenhoek was Anodon. His account is slight and 

 unsystematic. He mentions the ciliary motion in the 

 gills of this and a marine bivalve (Mactra?), but the 

 best of his attention was bestowed upon the eggs. 

 Ovarian eggs were studied by the microscope, and the 

 naturalist, his daughter and the draughtsman watched the 

 rotating embryos for hours together with great delight. 

 He was aware that the eggs are transferred from the 

 ovary to the gill. 



Swammerdam too made a cursory examination of the 

 structure of Anodon, from which he prepared a meagre 

 and largely erroneous description.^ Poupart and M^ry 

 (infra, p. 234) were the first to treat the anatomy of 

 Anodon with any thoroughness. 



1 Anatome Mytili, Belgice Mossel, stnicturam degantem ejuaque motum miran- 

 dum exponens. Prefixed to a Century of Medical Observations. 8vo. Amst. 

 1683. 



^Epist. 95, Cont. Arc. Nat. (1695). Vol. II, pp. 14-29 {2nd pagination). 



2 BiUia Naturoe, p. 190, pi. X, figs, vi, vii. 



