30 MORPHOLOGY OF PROTOZOA 



(Fig. 96). They are less often seen in the encysted stages of Entamoeba 

 coli. Like the glycogenic or iodophilic body in the encysted form of 

 lodamoeba hutschlii, they disappear in the course of a few weeks after 

 escape of the cysts from the intestine, apparently serving as a supply of 

 nourishment for the enclosed amoebae. 



Another type of cytoplasmic inclusion is the chromatophore, which is 

 characteristic of many plant-like flagellates grouped amongst the Phyto- 

 mastigina (Fig, 130). These are bodies which contain various pigments 

 known as chromatophyll. When green it is called chlorophyll, and when 

 red haematochrome. As in plants, these bodies enable the organism to 

 utilize the carbonic acid of the medium in which they live. It has been 

 show^n that the chromatophores multiply by fission in the cytoplasm, as 

 also do certain granules known as pyrenoids which may be present in the 

 chromatophores. It has been surmised that the chromatophores may be 

 symbiotic organisms living in the cytoplasm. 



In the process of ingesting solid food many Protozoa actually ingest 

 other forms, or even their own species, either in the free or encysted 

 condition (Fig. 99). The writer has seen a large vacuole in Entamoeba 

 muris of the mouse filled with actively motile Triclioynonas. The in- 

 testinal amoebae of man frequently ingest the encysted forms of other 

 intestinal Protozoa. In many cases the ingested organisms are killed 

 and digested, but this is not always the case. Instances are known in which 

 amoebae and even ciliates may have their cytoplasm riddled with vacuoles 

 in which smaller amoebae or flagellates occur. These may eventually 

 escape apparently unharmed by their stay in the cytoplasm of another 

 organism. Protozoa are also liable to invasion by bacteria. Such a 

 condition approaches, and may actually be, one of parasitism. Instances 

 of true parasitism are seen in the invasion of the body of Parameciimi by 

 the Suctorian Sphcerophrya pusilla (Fig. 534), and of various intestinal 

 flagellates and amoebae by Sphcerita, a vegetable organism which often 

 resembles a cluster of large cocci (Fig. Ill, 4). The inclusion of smaller 

 organisms within the cytoplasm of larger ones has always to be remembered, 

 especially when a process of multiplication by the production of daughter 

 individuals within the cytoplasm of a parent is considered. The nuclei 

 of such forms may be mistaken for nuclei belonging to the host. A method 

 of reproduction of Pelomyxa palustris, a large multinucleated amoeba, 

 by the production of flagellated forms within vacuoles in its own cytoplasm 

 has been described by Schirch (1914). It seems not improbable that this 

 was an instance in which an amoeba had ingested, but failed to kill, a number 

 of flagellates which were present in the medium. Doflein (1916) mentions 

 an instance in which the cytoplasm of a ciliate, Stentor ca'rulevs, included 

 numerous small flagellate organisms. 



