. The anatomy, physiology, morphology and development of the blow-fly (Calliphora erythrocephala.) A study in the comparative anatomy and morphology of insects; with plates and illustrations executed directly from the drawings of the author;. Blowflies. 482 THE NERVOUS SYSTEM. however, a kind of neural crest is distinctly seen (Fig. 62), which passes into the epiblast on either side, from which the segmental nerves are developed. In the earlier stages, the ganglia extend the whole length of the embryo, one pair in each segment, as they do in Chironomus and the Tipulidae. As development advance
. The anatomy, physiology, morphology and development of the blow-fly (Calliphora erythrocephala.) A study in the comparative anatomy and morphology of insects; with plates and illustrations executed directly from the drawings of the author;. Blowflies. 482 THE NERVOUS SYSTEM. however, a kind of neural crest is distinctly seen (Fig. 62), which passes into the epiblast on either side, from which the segmental nerves are developed. In the earlier stages, the ganglia extend the whole length of the embryo, one pair in each segment, as they do in Chironomus and the Tipulidae. As development advances, the nervous chain in the Blow-fly embryo becomes considerably shortened, and the ganglia are drawn together and fused into the short, thick conical neuroblast, which in the recently hatched larva is not more than one-third the length of the body. They are thus shifted from the segments in which they were originally formed. At the time of the escape of the larva ffom the Kio. 62.—A section of an embryo of the Blow-fly about eighteen hours old, showing the neural crests and the diverticulum of the crelom between the ventral ganglia, ch, the chyle stomach ; d, dorsal vessel; », ;, the intestine ; w, a Mal- pighian vessel ; «, the neural crest; tr, tr, tracheal vessels. the segmentation of the neuroblast is very obscure, and the existence of a series of ganglia corresponding to those of the ventral chain, in more generalised Arthropods, is only indicated by slight furrows on the surface, and by the existence of ten pairs of nerves. Indeed, the number of ganglia appears to be reduced to six pairs, as if is in the Pupiparae, by the atrophy or great reduction in the size of the ganglia, corresponding to the posterior abdominal segments (compare PI. II, Figs. 7, 8,. 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 origi
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Keywords: ., bookcentury1800, bookcollectionbiod, bookdecade1890, bookyear1890
