36 BRITISH FJiESHWATER HELIOZOA. 



round some only of the pseudopodia these being 

 spaced at fairly equal distances apart; the substance 

 of the envelope appears to carry the spicules along 

 the pseudopodia, and this action causes those furthest 

 out to lie more or less parallel to the pseudopodial 

 axis. 



The pseudopodia which radiate from the colonies 

 were found by Penard to originate from the central 

 granules of the individuals ; they are characterised by 

 their great length and are usually perfectly straight 

 and thinly and evenly covered with plasma, although 

 occasionally this is disposed in a series of elongated 

 drops. 



When disturbed an individual or a colony is apt 

 to divest itself of most or all of its spicules, during 

 which process as the animal moves forward the 

 pseudopodia in the rear are bent backwards, two 

 often lying together, side by side in an investment 

 of plasma, the rejected spicules being left in the track 

 of the animal. 



Without special preparation little can be seen of 

 the plasma or its contents, everything being hidden 

 by the crowd of spherical green alga cells normally 

 living in symbiotic relationship within the body ; as 

 is usual in these circumstances contractile vesicles 

 are absent, but they appear to be developed when, as 

 occasionally happens, the algal cells are wanting. 



The nucleus is spherical and contains a large central 

 spherical nucleolus. 



The central grain is sub-spherical and has a central 

 granule which becomes visible after staining by 

 carmine. 



Microbes normally infest the outer envelope. They 

 are small, round, or ovoid, and are stated by Penard 

 to divide transversely; the same author considers 

 that the ciliates which often invade the body itself, 

 living there parasitically, are related to the genus 

 Blepharism.a. 



Archer considered this to be one of the handsomest 



