THE STUDY OF STRUCTURE. 355 



and had not the least idea that the little spot he ob- 

 served was a most intricate structure. 



The fact that Bichat, in his Anatomie Generate 

 (1801), speaks only of tissues, shows that the import 

 of cells was not realised at the beginning of the 

 nineteenth century. Little importance can be at- 

 tached to the " vesicles " and " Urschleim " which 

 Oken discussed in 1805, for this illustrious repre- 

 sentative of the '^ IN'aturphilosophie " did not con- 

 cern himself much with concrete details. The obser- 

 vations of Mirbel on the structure of embryos had 

 more objective worth. 



^^ A still closer approximation to the truth is found 

 in the works of Turpin (1826), Meyen (1830), Ras- 

 pail (1831), and Dutrochet (1837); but these, like 

 others of the same period, only paved the way for the 

 real founders of the cell-theory.'' * 



In the first volume of his epoch-making work on 

 the development of animals (1828), Karl Ernst von 

 Baer " made the following prophetic statement " : — 

 " Perhaps all animals are alike, and nothing but 

 holloAV globes at their earliest developmental begin- 

 ning. The farther back we trace their development, 

 the more resemblance w^e find in the most different 

 creatures. And thus to the question whether at the 

 beginning of their development all animals are alike, 

 and referable to one common ancestral form, con- 

 sidering that the germ (which at a certain stage 

 appears in the shape of a hollow globe or bag) is the 

 undeveloped animal itself, we are not without reason 

 for assuming that the common fundamental form is 



* Prof. E. B. Wilson, The Cell in Development and Inher- 

 itance, Sded., 1900, p. 2, 



