2o INANITION AND MALNUTRITION 



In Pleurotrichia, Joukowsky ('98) described a remarkable reduction in 

 length from 200^1 to 30^, or even 15/x, during inanition, with no visible degenera- 

 tive changes; the body becoming enlarged again upon careful refeeding. In 

 DUeptus gigas, Hertwig ('03) likewise observed a great decrease in size during 

 starvation. Death may be escaped by conjugation or encystment, a result 

 confirmed by Prandtl ('06). Hertwig's pupil, Allescher ('12) studied the changes 

 in DUeptus in more detail. In "hunger cultures" at 6°C, the animals lived 

 four or five days with estimated average loss of 56 per cent in volume; at 15 , 

 seven to twelve days with loss of 97 per cent; at 25 , five days with loss of 98 

 per cent; at 30 , six days with loss of 99 per cent in volume (length reduced to 

 less than one- tenth, and breadth to one-third of the initial). The DUeptus 

 has normally a very large number of minute nuclear particles, probably over 

 1,000, which become reduced to 50 or 60 somewhat larger particles during 

 starvation. The plasma is consumed more rapidly than the nuclear material, 

 and becomes darker in color, due to formation of brownish pigment. 



In Didinium nasutum, Thon ('05) noted two stages of inanition similar to 

 those found in Paramecium by Wallengren ('02). "Die Haupterscheinung 

 der ersten Periode ist das Verdauen der Einschlusse und ^Condensation des 

 Plasmas, in der zweiten wird das Plasma vakuolisiert und die Tiere encystieren 

 sich." In the first stage nearly all the individuals divide, and the contractile 

 vacuoles become enlarged (especially also in Spirostomum ambiguum) . In the 

 later stages the organs associated with the cytopharynx may become disinte- 

 grated and absorbed. The changes in the nucleus appear early and are quite 

 variable. Its horseshoe form may be preserved or distorted. The nuclear 

 membrane is persistent, but wrinkled; and the nucleoli lose their chromatin 

 content. Cell-division becomes impossible and encystment follows. 



Encystment following inanition was likewise found by Root ('14) in Podo- 

 pliyrae, and Mast ('17) usually obtained similar results in Didinium nasutum. 

 Recently, however, Mast and Ibara ('23) conclude that inanition does not 

 facilitate encystment in Didinium. 



Paramecium. — The effects of inanition upon Paramecium have been observed 

 by several investigators. Verworn ('00) noted remarkable changes in starving 

 paramecia. "Ihr Zellkorper war durch ein Anzahl grosser kugeliger Vakuolen 

 nicht nur vollkommen deformiert, sondern auch in seiner Struktur in tief- 

 gehendster Weise verandert." 



The first extensive study of starving paramecia was by Kasanzeff ('01), 

 a pupil of R. Hertwig. He found that Paramecium caudatum survives six to 

 nine days, with marked decrease in size. In five days, the average length 

 decreases from 0.232 mm. to 0.147 mm., and the breadth from 0.084 mm - to 

 0.042 mm. The endoplasm becomes transparent and the food-vacuoles dis- 

 appear; but abnormal vacuolation occurs later. The macronucleus at first 

 elongates, increasing in volume and in chromatin content; but in later stages it 

 decreases greatly in size, extruding small yellowish masses into the endoplasm, 

 and may finally become fragmented. Normal cell-division and conjugation 

 usually occur only in the earlier stages of inanition. The micronucleus shows 

 increase rather than decrease in size; it may divide with the later reunion of the 



