PHYSIOLOGY 121 



were first dissolved and excreted by the contractile vacuoles, as they 

 were seen collected around the vacuoles. When exposed to X-irradi- 

 ation, the symbiotic Chlorella of Paramecium bursaria disappear 

 gradually and crystals appear and persist in the cytoplasm of the 

 ciliate (Wichterman, 1948a). These crystals varying in size from a 

 few to 12m, are found mainly in the posterior region of the body. 

 Wichterman notes that the appearance or disappearance of crystals 

 seems to be correlated with the absence or presence of symbiotic 

 Chlorella and with the holozoic or holophytic (by the alga) nutrition 

 of the organism. 



In Amoeba proteus, Schubotz (1905) noted crystals of calcium 

 phosphate which were bipyramidal or rhombic in form, were doubly 

 refractile and measured about 2-5m in length. In three species of 

 Amoeba, Schaeffer (1920) points out the different shape, number and 

 dimensions of the crystals. Thus in Amoeba proteus, they are truncate 

 bipyramids, rarely flat plates, up to 4.5m long; in A. discoides, abun- 

 dant, truncate bipyramids, up to 2.5m long; and in .4. dubia, vari- 

 ously shaped (4 kinds), few, but large, up to 10m, 12m, 30m long (Fig. 

 43). Bipyramidal or plate-like crystals are especially abundant in 

 Pelom.yxa illinoisensis at all times (Kudo, 1951); the crystals of P. 

 carolinensis remain the same during the starvation of the organism 

 (Andresen and Holter, 1945; Holter, 1950). 



The crystals present in Protozoa appear to be of varied chemical 

 nature. Luce and Pohl (1935) noticed that at certain times amoe- 

 bae in culture are clear and contain relatively a few crystals but, as 

 the culture grows older and the water becomes more neutral, the 

 crystals become abundant and the organisms become opaque in 

 transmitted light. These crystals are tubular and six-sided, and vary 

 in length from 0.5 to 3.5m- They considered the crystals were com- 

 posed of calcium chlorophosphate. Mast and Doyle (1935), on the 

 other hand, noted in Amoeba proteus two kinds of crystals, plate- 

 like and bipyramidal, which vary in size up to 7m in length and 

 which are suspended in alkaline fluid to viscous vacuoles. These two 

 authors believed that the plate-like crystals are probably leucine, 

 while the bipyramidal crystals consist of a magnesium salt of a sub- 

 stituted glycine. Other crystals are said to be composed of urate, 

 carbonate, oxalate, etc. 



Another catabolic product is the haemozoin (melanin) grains 

 which occur in many haemosporidians and which appear to be com- 

 posed of a derivative of the haemoglobin of the infected erythrocyte 

 (p. 605). In certain Radiolaria, there occurs a brownish amorphous 

 mass which is considered as catabolic waste material and, in Foram- 



