1 6 INANITION AND MALNUTRITION 



transparent, on account of the disappearance of the food- vacuoles and similar 

 inclusions. In the later stages of inanition, a progressive vacuolation of the 

 endoplasm has been described in Trichosphaerium, Didinium and Colpidium; and 

 in Paramecium by all recent observers except Lipska. Such vacuolation of the 

 endoplasm apparently does not occur in Noctiluca and Pleurotrichia, however, 

 and Lipska's results indicate that even in Paramecium it is probably only an 

 indirect effect of inanition, being due primarily to other environmental factors. 



Changes in the Ectoplasm. — In all cases the cell-membrane and associated 

 ectoplasmic structures (cilia, trichocysts, cytopharynx, etc.) appear more 

 resistant than the endoplasm, but in the later stages of inanition they also may 

 be attacked and partially resorbed (in Noctiluca, Didinium and Paramecium). 

 Associated with these regressive changes, there is a progressive decrease in 

 motility and in other vital phenomena. 



Nuclear Changes. — The nucleus in general is much more resistant than the 

 cytoplasm, but may show changes in form with loss of chromatin content (in 

 A moeba, Gregarina, Didinium, Stentor, Dileptus) . In forms such as Paramecium, 

 with macronucleus and micronucleus, the former shows more distinct changes. 

 In the earlier stages of inanition it frequently elongates and enlarges. Later it 

 usually divides, and may show degenerative changes, with granulation, vacuola- 

 tion, fragmentation and variable extent of resorption. The micronucleus usu- 

 ally persists practically unchanged, although rarely it may divide with reunion 

 of the daughter nuclei. This persistence of the nucleus is a factor of great 

 importance for the survival of the organism during periods of inanition. The 

 less important constituents of the organism are usually consumed first, the most 

 essential apparently survive longest. The persistence of the nucleus during 

 starvation recalls a similar behavior when living cells are engulfed and digested 

 (e.g., by Trichosphaerium, according to Schaudinn) and in trypsin digestion 

 experiments. This may be of significance as indicating the presence of similar 

 enzymes during the autolysis of cells in starvation. 



Effects on Reproduction. — The relations of inanition to reproduction in 

 Protozoa have attracted much attention. Many observers have noted an 

 apparent stimulus to division resulting from a brief period of starvation (in 

 Stentor, Didinium and Paramecium). R. Hertwig ('99, '03, '03a), however, 

 observed that while under certain conditions fasting protozoa may divide more 

 readily than well-nourished, as claimed by Jickili ('02) and others, this does not 

 occur as a general rule. In Paramecium, which has been most extensively stud- 

 ied, divisions occur to a variable degree in the early stages of inanition, but 

 rarely or never in the later stages. According to Hertwig's theory, inanition 

 upsets the cell-equilibrium as expressed by the nucleus-plasma ratio; but the 

 relative increase in the nucleus may be equalized later by a reduction in chro- 

 matin, associated with the process of conjugation. The literature on the nucleus- 

 plasma ratio is reviewed by Erdmann ('12). 



Rolph ('84), who proposed a nutritive theory of sex, claimed that conjugation 

 occurs in protozoa when conditions result in an interference with their nutrition. 

 Thus sex is considered as primitively a form of hunger, which drives the organism 

 to engulf its neighbor ("isophagy"). A similar theory of sex was elaborated 



