ADAPTATIONS OF PLANTS AND ANIMALS 37 



all illustrated by clear and useful plates. Heide (1683) 

 wrote an account of the structure of the edible mussel 

 (Mytilus), in which mention is made of the ciliary 

 motion in the gill; Poupart (1706) and Mery (1710) 

 wrote accounts of the pond-mussel (Anodon). Swam- 

 merdam's elaborate studies of insects and their trans- 

 formations were followed up by a long succession of 

 memoirs by Frisch in Germany, Reaumur in France, 

 and (shortly after the close of the period now under 

 discussion) De Geer in Sweden. The extraordinary 

 diligence and power of Swammerdam and Reaumur 

 give a very prominent place in the biology of the seven- 

 teenth and eighteenth centuries to the structure and 

 life-histories of insects. The great generalisations of 

 comparative anatomy do not belong to this period ; 

 nevertheless, sagacious and luminous remarks are not 

 wanting. 



Adaptations of Plants 'and Animals : Natural Theology. 



Natural adaptations and some of the problems which 

 they suggest were much studied during this period. 

 Bock and Cesalpini had discussed still earlier the 

 mechanisms of climbing plants, aquatic plants, and 

 plants which throw their seeds to a distance. Swam- 

 merdam figured, not for the first time, the sporangia 

 and spores of a fern ; Hooke the peristome of a moss. 

 The early volumes of the Academic des Sciences con- 

 tain many studies of natural contrivances. Perrault 

 described the retractile claw of the lion, the pointed 

 papillae on its tongue, the ruminant stomach and the 

 spiral valve of a shark's intestine. He improved upon 

 Hooke's account of the structure of a feather, and his 

 magnified figures of a bit of an ordinary quill and of a 

 bit of an ostrich-plume might be inserted into any 



