800 SUMMARY OF CURRENT RESEARCHES RELATING TO 



remarkable transparent hyaline ovate lorica, opening teat-like at both 

 ends, and a vibratory membranous hood or velum almost equal to the 

 ventral length. The anterior extremity of the body is protrusible 

 from the lorica. Their length is *001 inch, and the non-vibratile 

 setose body-cilia are about two-thirds of this length, with shorter 

 stronger vibratile cilia at the entrance of the velum. 



Actinophrys sol.* — Dr. A. Gruber, dealing with the fusion of 

 two or more individuals in the Heliozoa, says, that unfortunately the 

 signification of this process is still obscure, and we are not in a 

 position to establish an analogy with the accurately investigated 

 conjugation in the Infusoria, since no alteration in the nuclei of the 

 united individuals has ever been observed, nor any fusion of the 

 nuclei. The difficulties of observation are enhanced by the fact that 

 it is often impossible to see the nucleus in the living animal. 



As Dr. Gruber had recently a somewhat rich collection of Actino- 

 phrys sol at his disposal, he tried, with the aid of Korschelt's staining 

 process,| to arrive at some conclusion upon these points. He has 

 not, however, yet succeeded so well as might be desired, and must, 

 he says, defer any decision until further observations have been made. 

 He has, however, become acquainted with some other peculiar facts 

 which are of interest, and which he thinks it advisable in the first 

 place to make known. 



Two specimens of Actinophrys sol were observed, one well-formed, 

 and another only about a third or fourth of its size ; scarcely had the 

 pseudopodia of the two touched than the smaller individual was 

 quickly drawn to the larger, and united with it. After the union was 

 complete, he fixed the animal and coloured it, when to his surprise 

 only one nucleus was present. The experiment was repeated several 

 times. 



The first conclusion was that a union had taken place not only of 

 the protoplasm, but also of the nuclei, but on fixing and colouring 

 the objects before their union was completed, it was found that the 

 small individuals did not contain any trace of a nucleus. Subsequent 

 examination showed a large number of the small forms to be without 

 any nucleus. 



The rapidity with which the blending process takes place on the 

 meeting of two individuals is remarkable : in from ten to fifteen 

 minutes at the most, the small Heliozoa are absorbed by the 

 large ones. It is the same when the Actinophrys does not take its 

 fellow, but another organism, with this difference, however, that in 

 that case the prey dies by contact with its enemy's pseudopodia, 

 while the smaller individuals of the same species do not cease to 

 show all the ordinary signs of life, indeed even an increased motion 

 of the pseudopodia, and regular pulsation of the vacuoles. Once the 

 author succeeded in bringing one after another three small ones to a 

 larger one, and they were all fused in a very short time. During 

 this process two flagellates were caught and devoured. Strangely 



* Zool. Anzeig., v. (1882) pp. 423-6. 

 ■f Cf. this Journal, ante, p. 574. 



