i io PROTOPLASM 



the streaming. This can be seen most beautifully at the 

 hinder end of an Amoeba of this kind when it is creeping 

 after the manner of an A. Umax. Corresponding to the 

 axial forward stream towards the anterior end, an axial 

 tract of fibrillse traverses the Amoeba, radiating out poste- 

 riorly into a tuft as a consequence of the protoplasm of the 

 hinder end being drawn in from all sides into this forward 

 current. 



That radially disposed protoplasm may, moreover, occur 

 occasionally in other Amoebse is shown by the following 

 casual observation. In one of my preparations of A. actino- 

 phora, I found an elongated specimen, one end of which was 

 modified into a clear rim-like expansion. Although the 

 characteristic envelope of A. actinophora could not be demon- 

 strated with certainty in this specimen, nevertheless I 

 consider it probable that it belonged to the species in 

 question. The broad margin (Plate IV. Fig. 3), which 

 without doubt represented the end of the Amceba occupied 

 in forward movement, was radially striated in the most 

 beautiful manner in its entire depth. Although the structure 

 of the margin was relatively pale, it could nevertheless be 

 most plainly made out that it was the result of a radial 

 arrangement of the alveoli. The protoplasm bordering on 

 the margin towards the interior appeared very sharply 

 reticulated with very dark nodal points, resulting from the 

 deposition of fine granules. I think the assumption, 

 that this beautifully radially striated margin was repre- 

 sented in life by an apparently hyaline border, is all the 

 more permissible from the fact that Gruber (1882) depicted 

 on his Plate XXX. Fig. 17, an Amceba actinopJwra with a 

 similar border, in which a radial striation is faintly indicated. 



Since Greeff has recently again doubted (1891) the 

 emptying to the exterior of the contractile vacuole of 

 Amoebae, I may notice that these studies gave me the 

 opportunity of observing very clearly, in several of the 

 Amoebae investigated, how the vacuole does not disappear 

 until it is in direct contact with the surface, and that during 

 the process it collapses from within towards the exterior. 

 Hence I have no doubt that it is emptied to the exterior. 



