21 



Fig. XI. — a and ft, An Infusorial, Enchelys pupa, os, the ciliated mouth 

 *, alimentary cavity ; an, the anus . When young, colorless ; older, 

 greenish. 



Fig. XII. — The Difflugia pyriformis (foraminifera, monothalamia). s, 

 the protoplasma ; v, the contractile vacuole with constant heart-like move- 

 ments (Systole and Diastole) ; sp, the pseudopodia. 



Fig. XIV. — a, ft, v, 8, s, Exemplifying the 5, different states of the con- 

 tractile space (vacuole), sp, space; r, rays: a, space contracted, rays filled ; 

 ft, the first ejaculation of the rays, with filled space ; v, the second time 

 filled rays ; 8, the second time emptied rays ; s, a moment before empty- 

 ing the space, momentany showing the rays. (Koelliker). 



Plate IV. — Fig. XIII. ft, an Infusorial, Vorticella microcostomum. tr, 

 the screw-like contracted stem ; n, Nucleus, including several nucleoli (Bal - 

 biani, Engelman) ; v, the vacuole ; ps, th« mouth ; c, the vibrating cilia 

 (ad oral ciliated peristome). 



Fig. XIII. — s, the same Infusorial in semi-partition ; tr, muscular stem ; 

 os, the mouth ; n, the semi-divided nucleus. 



Fig. XIV. — The Paramaecium aurelia, an Infusorial, of which only the 

 outlines have been drawn; os, the mouth; v, the contractile spaces; e> 

 short, and cc, long cilia ; cp, another contracted space, enlarged, showing 

 the second state. (Plate III. Fig. XIV. ft.) 



Fig. XV. — The Vol vox globator, an Infusorial. A globular jelly-mass, 

 surrounded and having imbedded many individuals of Volvox, which are all 

 connected together with a kind of proplasma-net. The larger balls in the 

 figure XV, are, according to Cohn, the reproductive organs. Figure XV. gg, 

 represents one of the small points by a high power of the microscope, 

 showing two pseudopodia, several connecting links, and a few vacuoles in 

 the protoplasma. 



The Fig. H exemplifies the different forms and developments of Hydra 

 vulgaris. Fig. H. VIII., a Hydra catching a Cyclops eg ; st, the alimentary 

 cavity ; tr. the truncus body stem ; s, the sucker or disk ; fig. H. VII., a 

 Hydra producing several persisting buds, cd ; /, the tentacles. Magnifi. 

 about ten diam. Fig. H. VI., a Hydre with two stem-buds Id ; os, the 

 mouth ; fig. H. II., a, ft, v, three Hydres, each magnif. about 20 — 25 diam., in 

 a more or less contracted state. Fig. H. V., an ovule (egg) ; c, epidermis. 

 Fig. H. ft ft., a horizontal tissue of a hydre-stem, with a bud cd ; pr, the 

 alimentary canal. Magn. 60 — 70 diam. 



Plate V.— Fig. H. III. bd, a young Hydre-bud, j ust appearing by expansion 

 of the ectoderm ; eb, a larger bud, a few days older, with four little ten- 

 tacles, body ciliated ; tr, the stem ; s, the sucker ; os, the mouth ; /, the 



