42 General Morphology of the Protozoa 



garines to oxidize leuco-derivatives of various dyes, and suggested that 

 such oxidations are effected partly with the aid of glutathione and vita- 

 min A, previously detected in mitochondria (35, 111). The localization 

 of cytochrome oxidase in mitochondria also has been determined for 

 Stentor coeruleus (224). 



Vacuome 



The term, vacuome, was introduced as a collective designation for 

 the vacuoles in plant cells (36). According to later views (72), the vacuome 

 is distinct from the mitochondria and shows several characteristic proper- 

 ties. It may be stained vitally with dilute solutions of neutral red and 

 certain other dyes which do not stain mitochondria. Furthermore, the 

 vacuome is not reliably demonstrated by mitochondrial techniques, al- 

 though often impregnated by Golgi methods. 



Cytoplasmic inclusions of Protozoa were probably first referred to as 

 a vacuome by Dangeard (37), although neutral-red-stainable granules 

 had been described much earlier. The vacuome, in microorganisms gen- 

 erally, consists of small globules or granules rather than obvious vacuoles 

 (39). The reverse is true in higher plants. The vacuome of Protozoa in- 

 cludes small inclusions (Fig. 1. 19, C, E, F) which are distinguishable from 

 mitochondria in vital staining with mixtures of neutral red and Janus 

 green B. In certain species, it is evident that the elements of the vacuome 

 are normal inclusions of the living organism. The available data (76, 77, 

 158) suggest that a vacuome is generally present in Protozoa, although 

 apparently lacking in Conchophthirius mytili (116) and disappearing 

 during encystment of Ichthyophthirius multifiliis (156). Elements of the 

 vacuome are scattered through the endoplasm in many species. In certain 

 gregarines (110), however, the distribution varies in different stages of the 

 life-cycle. Adhesion of neutral-red granules to newly formed food vacuoles 

 (Fig. 1. 19, E) also occurs in certain ciliates. 



The ability to segregate neutral red apparently is not limited to one 

 type of inclusions. Dangeard (38) stained not only the usual vacuome but 

 also the cortical "mucous granules" (sometimes called trichocysts) in cer- 

 tain Euglenida. Bush (16) also found two types of neutral-red granules in 

 Haptophrya michiganensis. Food vacuoles of Protozoa also are stainable 

 with neutral red but they are usually not considered a part of the vac- 

 uome, in view of their different origin and behavior. 



Guilliermond (72) has pointed out that the vacuome of plants func- 

 tions in segregation and storage of metabolic products, and should be 

 considered a part of the deutoplasm, or paraplasm, rather than living 

 protoplasm. The vacuome may have comparable functions in Protozoa. 

 As shown by micro-incineration, the vacuome of Paramecium caudatum 

 segregates appreciable quantities of minerals (162), and the number of 

 neutral-red granules decreases in this species during starvation (49). The 



