CHAP, ii The Differentiation of the Tissues 223 



The anatomy of the leaf of the Angiosperms attracted 

 the attention of Hofmeister in 1868, Naegeli and Schwen- 

 dener in 1869, and Leitgeb in 1871. The work of Naegeli 

 and Schwendener dealt partly with the distribution of the 

 tissues according to mechanical requirements. Perhaps the 

 most important memoir on the leaf that appeared altei 

 1860 was Chatin's work of 1874. Goebel also wrote upon 

 it in 1880. 



Allusion has been made in a previous chapter to the 

 general elucidation of the problems connected with the 

 morphology of the ovule and the seed. Anatomical research 

 on the same subject was not neglected, though Hanstein's 

 types were for many years the only ones studied. In 

 addition to the work of Famintzin and of Guignard in the 

 early eighties, Treub published a valuable contribution to 

 our knowledge of the ovule and the embryo in 1882, and 

 described very fully the development of the former in the 

 Loranthaceae. Campbell in 1898 and 1900 described the 

 development of additional monocotyledonous types of 

 embryo, choosing Lilaea and certain members of the 

 Araceae. The work of many writers on the embryo-sac 

 has already been alluded to. 



The Gymnosperms as a group were studied by many 

 botanists from the point of view of anatomy as well as that 

 of morphology. Among the workers on the subject perhaps 

 the first place must be given to Strasburger. Reference 

 has already been made to his earlier work of 1869 and 

 1872 ; his great treatise of 1891, Ueber den Bau und die 

 V errichtungen der Leitungsbahnen in den Pftanzen, threw 

 light upon many obscure anatomical points, especially of 

 the Conifers, the completeness of the description of which 

 was very remarkable. He showed that all Conifers that 

 have bordered pits on the tangential surfaces of the latest- 

 formed autumn wood are destitute of tracheides in their 

 medullary rays, and vice versa. Also that intercellular 



