200 I'ROF. ALLMA^^ OX THE BECEXT UESEAKCIIES 



of Aotinoph'ys sol, the only naked heliozoan in which swarm-spore 

 formation has been seen. 



It has quite the habit of Actinophrys sol, except in being much 

 smaller ; and it also agrees with it in most points of structure. 

 It has, however, one to three very small contractile vacuoles in- 

 stead of the single large vacuole which in Actinophrys becomes, 

 during the diastole, protruded like a bubble from the surface of 

 the body. 



Its reproduction has been observed by Cienkowski, who find* 

 this to be connected with a true swarm-spore formation ; but in- 

 stead of the locomotive germs being, as in other cases, thrown 

 off in large numbers, it is a remarkable fact that the whole 

 body changes into an oviform swarm-spore, with one or two cilia. 



This change is preceded by the originally coarsely granular 

 protoplasm becoming gradually homogeneous and the nucleus 

 more conspicuous. In the meantime the pseudopodia disappear, 

 the body assumes an oval form, and the nucleus changes its posi- 

 tion, passing from the centre towards one end. On this end we 

 soon perceive one or two cilia, by whose vibration the swarm- 

 spore, now completed, is carried away through the surrounding 

 water. Cienkowski, however, has not been able to follow tlie 

 swarm-spore through any further phases. 



Cilioplirys, like Actinophrys sol, also multiplies by constricting 

 off portions of its body ; ajidjlike Actinophrys, two or more indivi- 

 duals may unite'and fuse together into a simple mass. It is not 

 only the fully developed Ciliophrys which possesses this property ; 

 for two swarm-spores may also fuse with one another. He observed 

 a GiliopJirys dividing by constriction, when each half became 

 changed into a swarm-spore. These had already retracted their 

 pseudopodia and had developed cilia on their free ends, but still 

 remained at the opposite ends united to one another by a narrow 

 bridge. The connecting bridge now became suddenly bent so as 

 to bi'ing the sides of the two swarm-spores into contact and allow 

 them to fuse together, forming a single two-lobed body, each lobe 

 carrying its cilium and containing within it a nucleus. The fusion 

 becaine more intimate, and the bilobed body gave place to one of 

 a triangular form, on whose flattened base were still to be seen the 

 cilia and, in its interior, the two cell-nuclei. Its rapid motion pre- 

 vented his following its fui'ther changes ; and he is unable to form 

 any conclusions as to the real significance of the conjugation or the 

 ultimate destiny of the swai-m-spores. 



