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PROF. ST. GEOEGE MITAET ON 



successively coDtracting such applied pseudopodia, just as an Echi- 

 nus rolls itself over by contracting serially its adhering ambulacral 

 suckers. Many Eadiolarians also resemble Echinus in that they 

 use their spines as levers. Haeckel has observed a Lithomelissa 

 (a Polycystine form with spines round the mouth of its shell) 

 thus raise itself so as to apply the mouth of its shell to the floor. 



These creatures nourish themselves in the same manner as do 

 the Polythalamia, but with less rapidity and energy. Moreover, 

 in Eadiolarians the food does not reach the middle of the body 

 (as it does in Polythalamians), on account of the capsule, which 

 Haeckel never observed to be traversed by any particles of car- 

 mine or indigo supplied for experiments. 



They live on Algae, Diatoms, and Infusoria (especially on Tin- 

 tinnidce), and other small animal and vegetable organisms found 

 near the surface of the sea. Haeckel has observed Infusoria to 

 become paralyzed by the touch of the pseudopodia of Aulacantha 

 and Thalassicolla, a fact pointing to the existence in undifferen- 

 tiated sarcode of a power and property which becomes energetic 

 in the thread- cells of Coelenterata and other less lowly animals. The 

 food is absorbed into any part of the extracapsular sarcode which 

 the skeleton does not hinder it from reaching. They probably also 

 absorb organic matter dissolved in the sea- water. Very minute 

 objects may often be observed coursing centripetally along the 

 pseudopodia, together with the granule-streams. When the prey 

 is relatively large many pseudopodia surround it, draw it in and 

 close over it ; and thus food can be assimilated by the pseudopodia 

 themselves when the formation and conditionof the shell prevents 

 its penetration more deeply within the matrix. 



Haeckel speculates as to the possibly hepatic nature of the 

 yellow cells, considering it to be not unlikely that they may be an 

 incipient form of liver. But, in the first place, these cells may (as 

 has been said) be parasitic ; and, secondly, a liver is, as it were, a 

 comparatively late result of tissue-formation, and could hardly 

 exist in the admittedly tissueless Protozoa. 



Abundant silica is manifestly somehow obtained by Eadiolarians, 

 either from the sea-water itself or from their Diatomaceous food ; 

 and there must be a free interchange of nutritious matter through 

 the capsule (even if solid food does not pass through it), as, in so 

 many, part of the siliceous skeleton is intracapsular. If food does 

 ever pass through it, then the existence of the concretions within 

 it may be explicable as food-remnants, as before suggested. 



