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Dr. A. Gruber on Protozoa. 325 



mical space, if this comparison be permitted. And, indeed, 

 they would seem to be ruined fragments with which we have 

 here to do — that is to say, fragments of Ileliozoa not produced 

 by regular division, but by the breaking-up and repeated 

 fission of normally formed individuals. 



I shall perhaps hereafter have occasion to notice that such 

 a breaking-tip into small pieces is a very frequent if not even 

 a regular periodical phenomenon among the Infusoria*; and 

 tin's applies also, according to ray observations, to Actino- 

 phrys among the Heliozoa. I have previously made the 

 same observation, but without going further into it. 



In the present case it would appear that these disintegra- 

 tion-fragments, which, as we have seen, may possess a high 

 degree of individuality, do not perish, but gradually become 

 converted into perfect Actinophryes or pass into the body- 

 substance of others. 



Unfortunately the difficulties in the treatment and pre- 

 paration of these objects is too great to permit one to hope 

 ever to arrive at perfect certainty about them, and to 

 decide such a question as whether the non-nucleate indi- 

 viduals are able to produce a nucleus endogenously. It 

 seems to me that this hypothesis is not to be absolutely 

 rejected out of hand, especially in the case of a Heliozoan 

 which is pretty nearly allied to those Khizopoda in which 

 the first nucleus must at some time have originated freely. 

 We certainly can hardly give a satisfactory explanation of the 

 breaking-up of the Heliozoa (unless we regard it as patho- 

 logical), except that thereby a more rapid multiplication may 

 be attained. The whole process has some resemblance to 

 histolysis during the embryonic development of some of the 

 higher animals. Just as in the latter process we see many 

 layers of cells dissolve completely, to be afterwards built up 

 again Out of the ruins, so here unicellular organisms break up 

 into small fragments, which again become formed into new 

 individuals, partly by fusion with others and partly by their 



proper growth. 



In conclusion, I must still mention that frequently the small 

 non- nucleate elements, on coming into contact with the pseudo- 

 podia of the normal animals, suddenly burst asunder and break 

 up into a mass of granules, which, however, are nevertheh s 

 incepted. In one case a small individual had approached 

 an Actinophrys; and when it was involved in the pseudo- 

 podia of the latter, it broke up suddenly, so that nothing 



* These investigations have not yet reached that completeness which 

 would allow me to cite them here. 



