CHAPTER II 



STUDIES OF NON-PARASITIC PROTOZOA 



Trichosphtzrium Sieboldii. 



WE are probably as yet only at the beginning of our knowledge 

 of the parasitic protozoa, and whilst the Sporozoa and the parasitic 

 Flagellata have been closely examined, many points concerning the 

 Sarcodina and the Ciliata still remained to be inquired into. It is 

 probable that pathogenic amoebae, besides that which has been recog- 

 nised as the cause of amoebic dysentery, and ciliates other than the 

 Balantidium coli, 1 await recognition. As a probable explanation of 

 some old observations, and as a preparation for the evolution of 

 possible new discoveries, the following studies are given here. 



Among the sarcodina the Heliozoa are remarkable for having 

 pseudopodia in the form of slender rays of protoplasm, but apart 

 from this particular subclass there are other sarcodina that are 

 provided with definite slender pseudopodia. One of these, Tricho- 

 sphcerium (Fig. 2), was the object of a renewed study by Schaudinn, 

 and its life-history was fully described by him in 1899. Now, 

 although this is one of the non-parasitic forms of amoeba, it 

 demands attention, because it is only by making ourselves familiar 

 with the various phases of the higher forms that we can know 

 what to look for in their kindred that are modified by parasitic 

 adaptation. For this reason an outline of the life-history of 

 Trichosphczrium is given here. 



Trichosphtzrium is a marine amoeba, and is common in sea-water 

 aquariums. It is marked by great tenacity of life. The full-grown 



1 See Part I. of this work, p. 144. 

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