Outlines of zoology . entually, inthe alimentary canal of another earthworm the cyst bursts,the spore-cases are extruded, the spores emerge from theirfirm chitinoid cases. The young spore (sporozoite) is likea bent spindle (falciform), and seems next door to beingflagellate. It bores into a mother sperm cell, and from thisit afterwards passes as an adult into the cavity of theseminal vesicles. Intracellular parasitism and copious foodnaturally act as checks to activity, and the adult is allies of Monocystis occur chiefly in Worms,Tunicates, and Arthropods; none are known in Verteb
Outlines of zoology . entually, inthe alimentary canal of another earthworm the cyst bursts,the spore-cases are extruded, the spores emerge from theirfirm chitinoid cases. The young spore (sporozoite) is likea bent spindle (falciform), and seems next door to beingflagellate. It bores into a mother sperm cell, and from thisit afterwards passes as an adult into the cavity of theseminal vesicles. Intracellular parasitism and copious foodnaturally act as checks to activity, and the adult is allies of Monocystis occur chiefly in Worms,Tunicates, and Arthropods; none are known in Vertebrates. *02 PHYLUM PROTOZOA THE SIMPLEST ANIMALS Eighth Type of Protozoa—Gregarina Gregarina, a type of Sporozoa in which the cell is dividedinto two regions by a partition. Description.—Various species occur in the intestine ofthe lobster, cockroach, and other Arthropods. When youngthey are intracellular parasites, but later they become free inthe gut. They feed by absorbing diffusible foodstuffs, such a b i i i)-. Fig. 45-—Life history of Gregarina.—After Butschli. 1. Young forms (a, h, c) emerging from intestinal cells (); z.«.) nucleus of intestinal cell. 2. Two forms conjugating (C. blatiaruin). 3. Spore formation within a cyst. 4. Adult with deciduous head-cap (), and a cuticular partition dividing the cell into an anterior part {A) and a posterior part(5) ; «., the nucleus. 5. A spore within its spore-case (j^.c). as peptones and carbohydrates, from their hosts, and storeup glycogen within themselves. In many the size is aboutone-tenth of an inch. There is a firm cuticle of proto-elastin, which grows inwards so as to divide the cell intoa larger nucleated posterior region and a smaller anteriorregion, and also, in the young stage, forms a small anteriorcap. The cell substance is divided into a firmer corticallayer and a more fluid central substance. The protoplasmoften presents a delicate fibrillar appearance, suggestingthat of striated muscle. The nucleu
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
