THE GROWTH OF BIOLOGICAL IDEAS 153 



both burning and respiration are examples of oxidation. The 

 old ItaHan biologist Spallanzani corrected their one big error 

 not long before he died at the end of the century: the com- 

 bustion does not occur in the lungs, as Lavoisier and Laplace 

 had thought, but in the various tissues of the body. 



The cell theory was first foreshadowed in the seventeenth 

 century. The English microscopist Robert Hooke described 

 the cellulae of cork; the Italian Marcello Malpighi, the ultric- 

 ulae of various plants; and Nehemiah Grew, their cells or 

 bladders. The Dutch petty official Anton van Leeuwenhoek 

 frequently figured cells. He also discovered blood corpuscles 

 and saw the nuclei of those of fishes, but the time was not ripe 

 for an understanding of the fact that both plants and animals 

 consist of cells. The follow-up of these seventeenth century 

 discoveries was slow. Half way through the eighteenth cen- 

 tury Caspar Wolff, the epigenesist, held that both plants 

 and animals consist of ampullae, but rigid proof was lacking 

 and the science of cytology had yet to be born. At the be- 

 ginning of the nineteenth century a Frenchman, Mirbel, 

 maintained that the cell is the basis of all structure in plants. 

 That extraordinary and erratic genius Lorenz Oken, amid a 

 maze of fantastic writings, claimed that all organic beings— 

 not plants alone— originate from and consist of little blad- 

 ders. 



About the same time advances were made in other branches 

 of what we should now call histology and cytology. The 

 young Professor M. F. X. Bichat— he was to die almost at 

 once, at the age of thirty— was making the first comprehen- 

 sive classification of the tissues of the human body, strangely 

 enough, without using the microscope. In 1825 a much-over- 

 looked French scientist, F. V. Raspail, introduced the use of 

 iodine into microscopical studies to show the distribution of 

 starch in tissues by its intense blue reaction. He thus founded 

 the science of histochemistry , and went on to devise tests for 

 other substances occurring in plant and animal tissues. 



From about 1830 onward cytology progressed rapidly, as 

 though in anticipation of the events of 1838. The versatile 



