184 



THE AMERICAN MONTHLY 



[October, 



would be rash. 1 will only say that 

 so many phenomena point to the ex- 

 istence of an endo-skeleton consisting 

 of two concentric reticulated spheres 

 with rays, partially solidified, but 

 soluble, that I accept this as the 

 probable anatomy of the creature. 



The extent to which solidification 

 has gone, and the degree in which it 

 is limited, seems to me to be indicated 

 by the movement of the rays near the 

 contractile vesicle when this expands 

 and collapses. As the vesicle grows 

 large like a great blister on the side 

 of the animalcule, the rays on either 

 side slowly widen their angle, and on 

 the collapse they quickly approach 

 each other, retaining the stiff, rod- 

 like character, and their true line of 

 projection from the centre of the 

 spherical mass. 



It has sometimes been stated that 

 the rays of Actinophrys cross each 

 other and grasp the prey ; the move- 

 ment being figured as if the rays 

 were analogous to the spines of 

 Echinus and movable from the surface 

 of the body. I have looked for some- 

 thing of this sort with great patience, 

 and have seen the animalcule capture 

 living things, times almost number- 

 less, but have never seen anything 

 like the process described. The radial 

 swinging of the rays when the con- 

 tractile vesicle collapses is the near- 

 est approach to it, and this, in the 

 case of two Actinophryes in conjuga- 

 tion, will, when the contractile vesicle 

 is near the junction of the two bod- 

 ies, cause the rays of the two to cross 

 each other on that side. In the cap- 

 ture of prey, however, the process, in 

 all the cases I have observed, is the 

 following : — 



If the captured object is minute 

 when compared with the captor, its 

 motion is instantly arrested when it 

 comes in contact with one of the rays. 

 In a moment it slides inward toward 

 the body, when a glairy and true 

 amoeboid pseudopod is extended 

 from the Actinophrys, irregular in 

 form, but approximately funnel- 

 shaped. This encloses the prey as in 



a capsule, which is then slowly drawn 

 into the body of the captor, which as- 

 sumes its regular outline. In some 

 cases the food is apparently found 

 distasteful, and is ejected again be- 

 fore being completely swallowed. 



If the captured object is large, as a 

 rotifer or a vorticella, the process is 

 different. A vorticella will be en- 

 veloped by a large capsule, often 

 larger than the body of the Actino- 

 phrys itself. In this extemporized 

 stomach the food will be seen as a 

 granulated, spherical mass, surround- 

 ed by the transparent capsule till di- 

 gestion is completed, when the ejecta 

 will pass out through the capsule, 

 and the Actinophrys will resume 

 its usual form. During the process it 

 will have the general outline of the 

 double form, as seen, in conjugation, 

 except that the rays will be seen only 

 on one of the lobes, the other look- 

 ing like a large, hyaline cell of equal 

 size, but an excrescence on the ani- 

 malcule. 



In the case of carapaced rotifers, or 

 large diatoms, the prey is more com- 

 pletely received into the body of the 

 animal ; but this has been so well 

 figured in the ordinary books of 

 reference, that I will not delay upon 

 it. The point I desire especially to 

 note is, that in all these processes 

 I have detected no movement of the 

 rays, except such as were plainly me- 

 chanical and fully accounted for by 

 the movements of the body in which 

 they were planted. They, together 

 with any connected endo-skeleton 

 which may exist, are forced aside to 

 make room for a diatom, etc., but I 

 could observe nothing akin to spon- 

 taneous or voluntary movement. 



The powerful stinging or benumb- 

 ing effect of the rays of Actinophrys 

 was exhibited in cases like the follow- 

 ing. A Rotifer vulgaris, moving 

 across the slide by doubling itself 

 like a measuring worm, came in con- 

 tact with the animalcule and, being 

 evidently hurt, made violent efforts 

 to get away. In these, the hinder 

 part of the body seemed to have lost 



