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alcohol animal appear arch archenteron arrangement base becomes blastopore blood body brain branches branchial canal cavity cells cent changes chitinous closed common completely condition connection consists containing continuous contraction covered described digestive dorsal ectoderm embryo endoderm epithelium existence experiments extends external fact fibers figures folds four fourth ganglion give given glands groove head heart increase Insects lateral layer length longitudinal lower mass median membrane minutes muscle nearly nerve neural tube nuclei observed obtained ommatidium opening organ origin pair passes pigment Plate pocket portion position posterior present probably processes regarded region represented retinula retractors says seen segments separated shown side similar single solution species specimens stage structure surface taken temperature tentacles third tion tissue tube ventral wall whole yolk
Seite 310 - Suppose, however, some solid and opaque particles of pigment deposited in certain cells of the the skin. Their opacity would arrest and absorb the light, thus increasing its effect, while their solidity would enhance the effect of external stimulus. A further step might be a depression in the skin at this point, which would serve somewhat to protect these differentiated and more sensitive cells, while the deeper this depression the greater would be the protection.
Seite 441 - ... that it may possibly have a function similar to that of the oil glands in birds. It differs in structure in different genera. In Podura, Lipura and Anurida it is a simple cleft tubercle. In Tomocerus it is enlarged, forming a tube, bilobed at the tip. In Smynthurus it has a similar structure, but " from the end of the tube the animal can project two long delicate tubes provided at their extremity with numerous glands.
Seite 445 - ... eighth joints are fused into one long piece, the sixth being much the longest of these three joints. At the anterior end of each joint, around the rim of the cup, there is a row of rather short stiff spines. There are also a variable number of spines scattered over the surfaces of the several joints. The mouth is situated on the ventral side of the head and, on account of the arrangement of the mouth parts, is placed so far posteriorly that it opens at a point posterior to the junction of the...
Seite 432 - Sur les jeunes individus, la disposition est tres curieuse, la figure 9 en donne une ide'e ; il existe alors 22 a 24 espaces comprimes et...
Seite 486 - Eisig, H. Monographie der Capitelliden des Golfes von Neapel. Fauna und Flora des Golfes von Neapel, XVI.
Seite 241 - They may be rendered more distinct by adding to the urine a few drops of a solution of iodine in iodide of potassium, which gives them a brownish tint.
Seite 491 - 81. Scudder, SH The structure and affinities of Euphoberia, Meek and Worthen, a genus of Carboniferous Myriapoda. Am. Journ. of Sci., Ser.
Seite 319 - This view of the ommatidium finds its strongest support in the fact that in Limulus the ommatidium is an open pit of the skin. By supposing that the ommatidial pit of...
Seite 432 - ... contre les autres avec une espace central libre : le tout rappelle la form du fruit chez les plantes malvacees indigenes entre autres les Malva et les Althaea. Quelque soin que j'aie mis a chercher si du point central il naissait un poil allonge ou toute autre production dermique, je dois dire que je n'en ai point trouve.
Seite 310 - Lubbock1 advances essentially the same idea as Balfour's in his recent work on the subject, illustrated with some lucid diagrams. " In the simple forms," he says, " the whole surface is more or less sensitive. Suppose, however, some solid and opaque particles of pigment deposited in certain cells of the skin. Their opacity would arrest and absorb the light, thus increasing its effect, while their solidity would enhance the effect of external stimulus. A further step might be a depression in the skin...