438 Gary N. Calkins. 



papilliform external swellings of the trichocysts and as merely 

 condensed peripheral portions of the cortical plasm. My own 

 observations support those of Wallengren. 



The third type of granule is interpreted by Prowazek as a 

 ferment or enzyme bearer. Putter, on the other hand, believes 

 them to be "respiratory granules" owing their staining capac- 

 ity to the contained carbon dioxid. Wallengren's observations 

 on starving forms led him to the belief that neither interpretation 

 is correct, for, he argued, these granules being the first to disappear 

 in hungry forms must be of the nature of stored food (see Figs. 

 23 and 24). 



The crystals which are found in well-fed forms were identified 

 by Schewiakoff as metaphosphate of calcium. They are of 

 various forms and sizes and are confined to the endoplasm; being 

 crystalline in nature they cannot be mistaken. They are now 

 generally regarded as late metabolic products resulting from pro- 

 teid digestion. 



b. The Ectoplasm. As in the majority of holo- and hetero- 

 trichida the ectoplasmic modifications are well diflPerentiated from 

 the endoplasm. A cuticle and underlying cortical plasm may be 

 made out, the latter consisting of a much more dense substance 

 than the endoplasm, analogous, probably, to the ectoplasm of an 

 amoeba. In it are embedded the characteristic trichocysts 

 which ordinarily project ever so slightly from the surface, giving 

 rise to the minute papillae which may be distinguished in profile 

 between the furrows of the cilia (shown in Fig. 20). In Para- 

 moecium taken fresh from the pond water, the fixing agent which 

 I have used, preserves the trichocysts within the cortical plasm, 

 but after a few months under cultivation these organs cannot be 

 made out, and seem to have been discharged and lost under the 

 stimulation of the fixing fluid. Wallengren believes that they are 

 taken into the endoplasm and digested as food in starving forms, 

 but in preparations made from my cultures they are absent in the 

 well-fed forms as in the degenerate ones. In all cases the spaces 

 that were occupied by the trichocysts are present in the cortical 

 plasm as vacuoles, and it is in this state that the relation to the 

 peripheral papillae can be easily made out (<:/. Figs. 13, 18, 20 



