114 Dr. A. Gruber's Contributions to the 



from above and behind^ whilst the clear border is due to the 

 sarcode which has flowed out of the aperture situated beneath. 



In Amosha actinophora this is certainly not the case, as I 

 think I have shown distinctly enough, and as will be under- 

 stood without further discussion by examining my fig. 11, in 

 ■which the cortex only shows a few remains (r s) , which have 

 already completely disappeared in fig. 12 ; or my fig. 16, which 

 represents the same example as fig. 9, which, without change 

 of place, underwent the alteration under my eyes. The 

 resemblance of A. actinojihora to Cochliojjodmm is still further 

 heightened when we see that the cortex also appears finely 

 punctate or lined, which struck me especially on the addition 

 of osmic acid (fig. 17). The hyaline protoplasm also then 

 appears finely punctate ; and the impression is produced as if 

 the finest granules effected the liquefaction of the cortex by 

 the reception of more fluid constituents between them. 



A great similarity to tlie Amoeba here described is presented 

 by the Jlhizopod represented by Hertwig and Lesser as a 

 doubtful form in fig. 8 A, as will be seen from a comparison 

 with my fig. 10. In this, however, the envelope (which is 

 even of a yellowish colour) is evidently much thicker. 



We may therefore demonstrate a perfectionation of this 

 structure from Amceba tentaculata^ through A. actinophora, to 

 Cochliojjodium. It might be conceived that by a further 

 increased tenacity of the cortical zone we shall finally be led 

 to those forms of monothalamous iihizopods whose envelope 

 forms only a soft membrane closely embracing the sarcode, 

 and which is still so completely at one with the protoplasmic 

 body as to accompany it in all its movements, and to be con- 

 stricted simultaneously in the division. 



Glancing back once more upon the phenomena which confront 

 us in the Amoebiform Iihizopods surrounded by a distinct 

 cortical zone, we shall find in them a welcome elucidation of 

 conditions such as have only been guessed at in the case of 

 other Amoebce. 



In the sarcode-body more fluid and less fluid constituents 

 are present ; the former we find at the spots which betray a 

 centrifugal movement, whether in the pseudopodia or in the 

 advancing part of the flowing Amoibie [A. quadrilineata, 

 villosa, ttntaculata, &c.). The heavier constituents remain 

 behind and are dragged along; and weseetliem finally break 

 into many cushion-like processes of hyaline proto]>lasni. 



The pushing forward of the more fluid constituents is 

 effected by the action of a pressure upon the opposite side ; 

 this is produced by the outermost layer of protoplasm at this 

 part acquiring a tougher consistency by extraction of water. 



