148 M. E. Penard's Notes on some lleliozoa. 



c. The chief body of the spicule is already perfectly 

 distinct when the base and the head are still scarcely so. 



d. In the adult the base and the fork at the apex always 

 remain more indistinct than the body of the stem ; the fork, 

 of a dull blue colour, is, as it were, implanted upon the stem, 

 which seems as if truncated behind the bifurcation. 



e. The body of the spicule perfectly resists concentrated 

 sulphuric acid, as also a red heat, while the head and the base 

 disappear ; but after the action of these reagents the spicule 

 is then traversed in this species by a central line, which is 

 brownish by refraction and seems to show that it is hollow, 

 as indeed Greeff has already stated. 



f. The spicule, especially when young 1 , seems to be covered 

 with a very fine mucilaginous varnish. This may be inferred 

 from the appearances in the living animal, then after simple 

 desiccation, and finally in glycerine, or from the effects pro- 

 duced by the action of an acid. 



From these observations, checked by others made upon 

 three different species {Acanthocystis aculeata, erinaceus, and 

 albida) which have given me the same results, I think it is 

 permissible to draw the following conclusion : — " The spicules 

 of the A canthocy slides are clothed, at least during the time 

 of their growth, with a mucilaginous varnish, witlsin which 

 they are formed. Their growth takes place at the same time 

 at the base and at the apex." 



I may add that, having found in January last in one of 

 my bottles a great quantity of young individuals belonging 

 to Acanthocystis albida y sp. nov., and examined them from 

 time to time, at each observation I found their radial spicules 

 more vigorous, so that in three months their thickness and 

 length were nearly double what they were at the first obser- 

 vation ; later on these animals remained stationary and died 

 in water which no longer furnished them with food. As. 

 there is scarcely any doubt that I had constantly to do with 

 the same generation, we must infer from this that these 

 animals took three months at least to arrive at the adult 

 state, and that their life is consequently tolerably long. 



Another point in the physiology of the Heliozoa which is 

 still obscure regards the movements of the animal, and leads 

 me to say a few words on the pseudopodia. 



Here again we find a well-marked difference between the 

 Actinophrydians, that is to say the genera Actinophrys and 

 Actinosphcerium on the one hand, and the rest of the Heliozoa 

 on the other. The pseudopodia of Actinophrys consist of a 

 hyaline axial thread, which, however, is rarely visible. 



