35 Elementary Biology. 



all tissues were cohiposed of minute saccules, to which he 

 applied the name of 'cells.' Schwann (1810-1882) was 

 similarly the first to apply the same generalisation to the 

 tissue of animals, and so to aid in enunciating the cell 

 theory on which modern morphological research for the 

 most part rests. 



Cells were found to vary greatly in size and shape, and 

 a collection of similar cells formed a tissue. Every plant 

 and every animal examined told the same tale. Organs 

 made up of different kinds of tissues, tissues composed 

 of collections of similar cells. Not only so, but every 

 organism in the earliest stage of its existence was found 

 to be composed of a single cell, which by division gradu- 

 ally became first a minute cellular mass, then by differen 

 tiation of cells a collection of tissues with different duties 

 to perform, and finally an adult plant or animal, as the 

 case might be, with tissues composed of different cellular 

 elements united to form organs concerned in the main 

 tenance of individual or of tribal life. 



This takes us well into the nineteenth century, and its 

 early years bring us face to face with all those names that 

 we are most accustomed to associate with biological progress. 

 Geoffrey S. Hilaire (1772-1840) and Von Humboldt (1769- 

 1859) had begun their researches into the distribution of 

 living organisms, and Lamarck (1744-1829), working, on 

 the material collected by Cuvier and the anatomical schoo'l 

 of zoologists which he had founded, had made his guesses at 

 the origin of living things ; guesses which were destined in 

 after years, in Darwin's hands, to become organised into the 

 theory of evolution by natural selection. 



Lamarck's generalisations were greatly in advance of the 

 age in which he lived. To write a book in those days in 

 support of the view that 'all species, including man, are de- 

 scended from other species ' was unlikely to lead to any other 

 result than to arouse suspicion as to the sanity of the author. 

 Lamarck, however, despite the risk he ran, published his views 



