ANIMAL NATURE OF DIATOMEjE. 507 



does not at all participate in the successive changes that 

 these undergo in germination. 



Page 10. — Nageli has digested in an able manner all 

 the facts relating to vegetable movements. The first 

 series of movements is intimately connected with growth, 

 and in regard to this we do not possess sufficient data to 

 establish a general difference between the two organic 

 kingdoms. The second is referable to the difierent 

 positions assumed by various organs of plants under the 

 influence of external agents ; and those movements are 

 explained by an accumulation of juices in determinate 

 tissues, excited by these agents, or by the elasticity of 

 the cellular membrane. The movements of individual 

 parts of certain organs are mechanically produced by the 

 desiccation or intumescence of various tissues. But still 

 the question remains almost untouched in respect to the 

 locomotion of the inferior Algae, sporidia, spores, and 

 spirilla. The impulse communicated by endosmosis and 

 exosmosis, has certainly a large share in the phenomena ; 

 but, after all, there remains the fact of vibratile cihae, 

 which seem to take part in these movements. 



Page 12. — The Protococcus and Gregarina are beings 

 that 'present the greatest degree of simplicity in their 

 permanent state. Though, down to 1842,1 had limited 

 the genus Frotococcus to those vegetable beings only 

 which really present the greatest possible simplicity, other 

 authors, and Kiitzing in particular, continue to insert 

 species of more complicated organisation; hence some 

 confusion is created whenever we refer to this example 

 of organic simplicity. 



I admit into the genus Protococcus only those vegetables 

 which, according to our means of observation, are reduced 

 to a simple cell. When the period of reproduction arrives, 

 the wall of this cell is either reabsorbed, or is lacerated, 

 and its contents are poured out ; the rudiments of new 

 individuals make their appearance, which are never visible 

 in the cavity of the maternal cell. The development of 



