126 PROGRESS OF SCIENCE. 



discovered that lower animals (worms, lobsters, polypes, for 

 instance) have the property of growing afresh limbs and 

 organs lost by fracture, maybe such as heads, tails, legs, 

 e tc. a study pursued concurrently and carried further by 

 Spallanzani. Some animals (the aquatic salamander, for 

 example) were shown by these two physiologists to grow the 

 same limb eight times in succession. Bonnet in his Contem- 

 plation of Nature threw out the first suggestion of PROGRESSIVE 

 EVOLUTION from the lowest organism to the highest a 

 subject developed later by Lamarck and fully analysed by 

 Darwin. 



1729 99. Spallanzani made decisive experiments upon 

 microscopic ANIMALCULA ; determined the FORCE OF THE 

 HEART upon the arteries, and the relative speed of the blood 

 through the different channels ; showed Infusoria to be 

 oviparous, viviparous, and hermaphrodite; pointed out the 

 principle of DIGESTION IN INSECTS. Like Bonnet, he ex- 

 perimented upon the power of regrowth possessed by lower 

 animals, such as snails, water-salamanders although some, 

 like the last-mentioned animal, have, as he showed, a heart, 

 red blood, lungs, bones, muscles. Spallanzani also studied 

 the vegetable kingdom, and pointed out numerous phenomena. 

 In the course of the XVIIIth century, biology may be said 

 to have made great strides through the labours of Haller, 

 Bonnet, Spallanzani, and Hunter, independently of the 

 immense work of Linnaeus, Buffon, and Lamarck. 



17481794. Vicq d' Azir studied the NERVOUS SYSTEM 

 with a thoroughness never surpassed in his time; and he 

 established the LAW OF HOMOLOGY, which will become later 

 the subject of a great scientific battle. 



17491823. Jenner originated VACCINATION, one of the 

 greatest benefits for which humanity is indebted to science 

 and an innovation in meeting disease which will bear rich 

 fruit in the XlXth century inoculation becoming then a 

 subject of deep researches and experiments. 



1773 1858. Brown (Robert), concurrently with MOL- 

 DENHAUER (17661827) and MIRBEL (1776 1854), studied 

 the physiology of plants and greatly extended our knowledge 

 of the formation of the seeds, the structure of the cells and 



