EFFECTS ON THE PROTOZOA 1 9 



das Protoplasma im Innern der Zelle in Angriff genommen wird. Audi der 

 Kern zeigt geringe Veranderungen. Nach dem fliissigeren Innenplasma, wird 

 das festere periphere Plasma als Energiequelle fur den Stoffwechsel benutzt, 

 sowohl Bestandteile der Zellmembran wie auch der Organellen, Staborgan, 

 Tentakel, Zahn und Lippe." 



Infusoria. — Among the Infusoria, the Paramecium has been studied most 

 extensively, but some observations have also been made upon other species. 

 Gruber ('86) noted cell-divisions with decreased size in malnourished Stentor 

 coeruleus. The phenomena were more carefully described by Maupas ('88), 

 who experimented at temperatures of 23-26°C. with the following results: 

 "Lorsqu'on prend un Stentor bien nourri et arrive a son maximum d'accroisse- 

 ment, et qu'on l'isole en le privant completement d'aliments, il n'en continue 

 pas moins a se multiplier. Mais chaque bipartition n'etant plus suivis d'accro- 

 issement, la taille diminue rapidement et apres trois ou quatre divisions, on 

 arrive a. ne plus avoir que de petits avortons mesurant 235/z en longeur et 105^ 

 en largeur (PL XII, Fig. 14). Si on continue a laisser ces avortons sans nourri- 

 ture, ils s'etiolent de plus en plus et finissent par perir apres deux ou trois jours. 

 Mais en leur donnant une abondante nourriture, je les ai vus en deux jours, 

 par une temperature de 24 a 25 degres, s'accroitre rapidement et reprendre leur 

 taille normale de 1176M en longeur et 270^ en largeur (PL XII, Fig. 15)." 



Further observations were made by Sosnowsky ('99), who noted, in Stentor 

 coeruleus fasting in distilled water, the appearance of nuclear vacuoles, often 

 collapsing at the periphery so as to give an irregular nuclear contour. Allescher 

 ('12) in the same species found the rate of loss during starvation to vary greatly 

 according to temperature. Thus the loss in volume after three days at 6°C. 

 averages 18.53 per cent; at 15 , 41.21 per cent; at 25 , 60.03 percent. Frequency 

 curves of distribution in size were made. ''Pure line" cultures show no reduc- 

 tion in size variations. The nuclear substance shows no decrease in the 

 cold (6°) cultures, but at higher temperatures there is a reduction in the 

 size and number of the nuclear masses, and sometimes the nuclear chain 

 is broken. 



In Colpidium, Miyoshi ('96) and Jensen ('99) observed during inanition a 

 diminution in size and a disappearance of the cytoplasmic granules, with 

 resultant increase of transparency. Wallengren ('02) also noted vacuolation 

 of the endoplasm during the later stages of starvation in Colpidium, together 

 with other changes similar to those found in Paramecium (to be mentioned later). 

 Peters ('20, '21) observed that in cultures of Colpidium colpoda in synthetic 

 nutrient mixtures the structure is not easily modified by chemical changes in 

 the medium. The size of the organism may be reduced by inadequate nutrition, 

 but is regained by new subcultures on adequate diet. Experiments indicate 

 that ammonium phosphate and chloride, and also magnesium salts, cannot be 

 omitted from the medium without stopping growth. Phosphate deficiency 

 causes apparent disintegration, and potassium deficiency results in loss of 

 movement, with final death. However, sodium, calcium or sulphates may 

 apparently be separately omitted (excepting traces) without injurious 

 effects. 



