. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). 8UDKIN0D0M PROTOZOA. 29 forms, such as Motms, iu which no cuticle is deveh)pe(l, uo special luouth-oritice is present, though the in- gestion of food tiikes place at a more or less deMuitely localized region at the base of the Hagellum, the food-particles drawn to the organism by the currents established by the ilagellum usually impinging at this point; where, however, a detinito cuticle or shell is developed a definite mouth occurs, and in some cases, as Euglena (Fig.
. A textbook of invertebrate morphology [microform]. Invertebrates; Morphology (Animals); Invertébrés; Morphologie (Animaux). 8UDKIN0D0M PROTOZOA. 29 forms, such as Motms, iu which no cuticle is deveh)pe(l, uo special luouth-oritice is present, though the in- gestion of food tiikes place at a more or less deMuitely localized region at the base of the Hagellum, the food-particles drawn to the organism by the currents established by the ilagellum usually impinging at this point; where, however, a detinito cuticle or shell is developed a definite mouth occurs, and in some cases, as Euglena (Fig. 13, B), this leads into a distinct tubular pharynx projecting some distance into the interior. No hollow digestive tract is, however, present, but the food-parti- cles, after traversing the gullet, are received directly into the protoplasm of the body, and are digested there as in Amceha. A localized egestive region, situated usually towards the posterior end of the body, has been ascer- tained to occur in some species, but in no instance is it a permanent orifice, as is the case with the mouth. In addition to the nucleus, contractile vacuole, and food-particles, other definitely organized particles, such as starch-like granules and pigment-granules, may be imbedded iu the protoplasm. In Euglena the pigment is green and resembles plant-chlorophyll, probably too possess- ing a similar function. A red pigment-spot (stigma) is rise present iu this and other genera at the base of the flagellum and is supposed to be concerned in light-perception. The typical Flagellate is a free-swimming single organism, but many forms are fixed, developing a stalk by which they are fastened to foreign bodies ; the stalk may be very much branched, each terminal branch supporting an individual, the whole thus forming a colony, without, however, any differ- entiation among the individuals. Free-swimming colonies also exist, such for example as Volvox^ in which a large number of individuals are group
Size: 1680px × 1487px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
