I02 PALMER : 



vided with this raphe which exhibit the liveliest tuotions. It 

 is true that a number of species not provided with a technical 

 raphe also move more or less, each after its own fashion ; but 

 those others have something just as good, and in fact some- 

 thing quite of the same nature. Such is Nitzschia, with two 

 longitudinal keels, each furnished from end to end with the 

 smallest imaginable cleft. Such also is Siirirella, with four 

 keels, each with its very narrow cleft. These move with 

 vigor. Campylodiscus has similar clefts near the edges of its 

 bent discs, and it goes along haltingly. Etinotia has short 

 raphes at its corners, and here again is power of motion with 

 peculiar features. Synedra, very long and narrow, has noth- 

 ing but dot-like openings at its ends, and can rear itself on 

 end from a perfectly flat surface, but no one has claimed for 

 it actual power of locomotion. Tabellaria and a multitude of 

 others, without visible openings classifiable as even rudiment- 

 ary raphes, have not been seen to move at all. We may 

 therefore be certain that the internal protoplasm acts directly 

 or indirectly through the raphe or its equivalent when pushing 

 itself along. No raphe, no motion ; no motion, no raphe. 

 Therefore it is that students of diatom motion have generally 

 confined themselves to the observation of the naviculoid 

 species, more particularly to those larger forms of Naviciila 

 often classed under the name of Pimmlaria. The work of 

 Hauptfleisch, however, was not on Pinnularia, but still on 

 naviculoid forms, though the raphe was not his principal sub- 

 ject, and as a direct consequence of this circumstance he 

 would seem to have been less fruitful in results than his con- 

 temporaries in this study. 



Omitting pioneer work, and ignoring mere theories, we 

 may say that direct contributions to our present subject are 

 found under very few signatures.* H. L. Smith, f O. 



* In what follows, reference will he to the papers here cited once for all. 



t A Contrihution to the Life-History of the Diatoniaceae. Proceed- 

 ings of the American Society of iMicroscopists, 1886-1887. A sunnnary 

 of Prof. Smith's views will he found in Van Henrck's Treatise on the 

 Diatomaceie, Knglish version, London, 1896. 



