OF MICRO-ORGANISMS. 7 



cous and elastic, and the central liquid contents hold- 

 ing granules in suspension. 



" From the time of the apparition of a pseudopod, a 

 current of liquid is visible which penetrates into the 

 pseudopod and which seems to contribute to its elon- 

 gation. It is very evident that the liquid is passive, 

 that it penetrates into the pseudopod only because, 

 pressed upon from all sides, it finds less resistance 

 there. I think that the (in appearance) homogeneous 

 hyaline substance of the pseudopod is also a species 

 of hernia of the estosarc, resulting from a diminution 

 of the elastic resistance at the point where it appears, 

 with an increase of elasticity or of contractility (to me 

 two modalities of the same property) in those parts of 

 the ectosarc where pseudopodia are not produced. 

 When the contractility or the elastic tension of these 

 parts diminishes, and returns to its original state 

 the pseudopod re-enters into the mass. Add to this 

 that, in an amceba of large dimensions, Amoeba terri- 

 cola, it has seemed to me that the most external mem- 

 brane of the ectosarc showed striae of a granular ap- 

 pearance which may be identical with the striae or con- 

 tractile fibrils of the ectosarc of the ciliated infusoria, 

 Stentor,Spirostomes> Bursaria, etc." (May 20, 1887.) 



The "pseudopod does not represent a permanent, 

 differentiated organ of locomotion; it is produced by a 

 simple prolongation of the mass of the body, which 

 can take place at any point whatever, and when the 

 act of locomotion has been accomplished, this pro- 

 longation re-enters into the common mass without 

 leaving any traces of its emission. In other animal 

 species, for example the Petalobus of Lachmann, 

 initial traces of differentiation of the pseudopodia 

 have been observed; they always form at the same 



