. A text-book of invertebrate morphology. Invertebrates. TYPE TBAOHEATA. 473 ends and in continuation with tiie optic nerve, have developed distinct rods (r) at their outer ends. In the lusecta and occasionally in the Myriapoda {Scuti- gera) there are in addition to these simple ocelli compound eyes, situated at the sides of tlie head and similar in structure to the compound eyes of the Crustacea. Each of the om- matidia of which the eye is composed, and there may be mgc. Fig. 216.—Sections thkough an Ocellus of a Larva of Acilius in (A) a Vbky Young and in (B) an Oldbk Specimen (after Patten)
. A text-book of invertebrate morphology. Invertebrates. TYPE TBAOHEATA. 473 ends and in continuation with tiie optic nerve, have developed distinct rods (r) at their outer ends. In the lusecta and occasionally in the Myriapoda {Scuti- gera) there are in addition to these simple ocelli compound eyes, situated at the sides of tlie head and similar in structure to the compound eyes of the Crustacea. Each of the om- matidia of which the eye is composed, and there may be mgc. Fig. 216.—Sections thkough an Ocellus of a Larva of Acilius in (A) a Vbky Young and in (B) an Oldbk Specimen (after Patten). ir = inverted rods. n = nerve. I = cornea. pg = pigment. mgc = median giant cells. r = rods. vb = vitreous body. several thousand of them in each eye, consists of an external cornea (Fig. 217, co), usually more or less hexagonal in outline, giving the eye a faceted appearance. Beneath the cornea are two cells which secrete it and form the corneal hypoder- mis, and below these again come four cells, the crystalline- cone cells, which may (euconous eyes) or may not {aconous eyes) manufacture a crystalline cone (c), and finally beneath >these is a circle of seven retinular cells (four in Lepisma), each one of which is pigmented and manufactures a portion of the chitinlike rhabdom {rli) which they surround; these cells are probably continuous at their inner ends with the optic nerve. Additional pigment-cells {pg) separate the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McMurrich, J. Playfair (James Playfair), 1859-1939. New York, H. Holt and Company
Size: 2013px × 1241px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1894
