

270 Dr. A. Gruber on Protozoa. 



of a flow or movement is to be observed in its interior. Never- 

 theless, when observed for a long time, distinct, although 

 slow, changes of form, in which the spiny part shares, make 

 their appearance. For example, the Rhizopod acquires a 

 band-like form instead of being globular as before ; and thus 

 it appears to increase in length under the eye of the observer. 

 In this way it frequently extends itself so much that the 

 bacilli become more widely separated from each other ; and 

 thus the view of the interior becomes freer. Such specimens 

 are particularly well adapted for the study of the issue of the 

 pseudopodia from the pores. 



In figure 2 I have represented a Pachymyxa which has 

 rolled the middle part of its body into a spiral form, having 

 been at first globular and then band-like. We distinctly see 

 the folds which the envelope makes over the tough proto- 

 plasm. Soon after the animal had acquired this form it 

 suddenly unrolled itself again, and then slowly regained a 

 rounded form. 



But we obtain a better knowledge of the structure of Pachy- 

 myxa and of the relations of the protoplasm to the envelope than 

 from the living animal by making preparations in which the 

 animals, after being killed with osmic acid, are stained witli a 

 solution of carmine and finally mounted in Canada balsam. 

 In the first place, we find that in this process the bacillar 

 envelope is separated as a whole from the protoplasmic body, 

 or the latter contracts from it. From this we see that, although 

 during life this envelope is so closely united with the sarcode 

 that it has to accompany it in all its movements, the bacilli 

 are nevertheless seated upon a special excessively thin outer 

 layer, somewhat like a cuticle, which, however, in life does 

 not separate from the rest of the protoplasm. I have obtained 

 reparations in which this fine membrane had actually become 

 ark-coloured, and thus became very distinctly visible. 



At the points where the pores are situated there must of 

 course be a gap in this outermost layer of protoplasm ; i. e. it 

 is no doubt perforated by each pseudopodium that issues forth, 

 to be formed afresh as soon as the pseudopodium is again 

 retracted. We cannot generally succeed in obtaining a prepa- 

 ration with extended pseudopodia ; but on some few occasions 

 I have managed this; and the conditions were particularly 

 distinct so long as the Pachymyxa continued lying in. the 

 staining- fluid, and therefore before the alcohol had exerted its 

 contractive influence. Figure 3 is drawn from such a prepa- 

 ration. We see in it the bacilli of the envelope far removed 

 trom the body and a pseudopodium issuing through a pore. 

 We further see at this point the layer of hyaline protoplasm 



