INFUSORIA. 



39 



dant in the fall. It may be said always to occur in these localities, together 

 with a rotifer, Anuroea longispina, which has singularly long anterior and 

 posterior spines corresponding in number with those of the infusorian. 

 The resemblance is striking. Mr. J. Levic has recently found the same 

 forms together in Olton Reservoir, near Birmingham, England. 



The species of the remaining families have one or more flagella (usu- 

 ally one), with the body more or less clothed with cilia; in some the 

 whole surface bears them, in others only a crown of cilia occurs at the 

 anterior end, the flagellum standing in the midst. Asthmatos ciliaris 

 (Fig. 36) exemplifies this structural peculiarity. This species occurs in the 

 mucus from the nasal passages of persons suffering from " hay fever," and 

 is held by Dr. J. H. Salisbury to be the cause of this distressing complaint. 



Fig. 36. — Asth- 

 Tnatos cilia/riSf 

 magnified 600 

 times. 



Order II. — CILIATA. 



The animalcules of this great order, as the name implies, possess cilia as locomotory 

 organs. They are much more highly organized than the Flagellata, and many of the 

 forms included are generally better known, and are more 

 generally called to mind by the name Infusoria. Stein's 

 division of the order into suborders is as follows: Holo- 

 tricha, with cilia over the whole surface ; Heterotricha, with 

 cilia distributed over the entire surface, having those near 

 or surrounding the mouth longer ; Peritricha, cilia mostly in 

 a wreath about the mouth ; and Hypotricha, with cilia on 

 the ventral surface only. 



Sub-Order I. — Holotricha. 



A common type of the first sub-order and of the family 

 Parameoid^ is Paramecium aiirdia (Fig. 37). It occurs 

 in hosts in vegetable infusions, stagnant pond-water, etc. 

 These active, elongate, animalcules are alike the delight of 

 the amateur microseopist and the joy of the veteran inves- 

 tigator ; it is to him what the frog is to the general anato- 

 mist and physiologist. It was made for investigation ; the 

 comparatively large size and transparent body fit it admirably 

 for study, and it has not been neglected. The anterior third 

 of the body is somewhat flattened and twisted, so that the 

 flattened face resembles a living figure of 8 ; near the middle 

 of the ventral face — at the posterior extremity of the 8 — 

 the mouth is situated. The rejectamenta issue at a point 

 about half-way from the oral aperture to the posterior ex- 

 tremity of the body. There are two contractile vacuoles near 

 the extremities. .When expanded they are round, but when 

 contraction takes place there appear fine radiating streaks, 

 which, as the main portion decreases, gradually broaden, 

 until, when the former is nearly invisible, they are extended 

 over half the length of the body. It has been suggested 



Fi6. 37. — Paramiecivm aurelia, 

 greatly enlarged. *, o. Con- 

 tractile vacuoles, d. Mouth. 

 e. (Esophagus, g, i. Food vac- 

 uoles, h. Nucleus, m. Eudo- 

 sarc. 



