scholarly journals NOTES ON THE EARLY STAGES OF LIXUS MACER, LeConte

1883 ◽  
Vol 15 (6) ◽  
pp. 113-113
Author(s):  
D. W. Coquillett
Keyword(s):  
Summer Season ◽  
Wild Sunflower ◽  
Pale Yellow ◽  
Early Stages

On the 13th of July, 1881, I saw a female L. macer busily engaged in gnawing holes in the stem of a green Helianthus grosse-serratus (Wild Sunflower). There were several holes in the stem of this plant, and in each I found one or two eggs, of an elliptic-ovoid form, polished pale yellow, and measuring about two and one-fourth mm. in length. In the stems of other similar weeds, which grew near to this one, I found several recently hatched larvæ. I examined the stems of this same kind of weed at intervals throughout the summer season, and found the larvæ in different stages of their growth, sometimes two or three in the same plant. Late in October I noticed that many of these weeds had been broken off, and the pieces—from one and a half to three feet in length—were lying about upon the ground. These pieces contained a larva—evidently of the above species—and at one end, and occasionally at each end, the pith and woody part had been gnawed away, leaving nothing but the bark, and this had evidently been broken off by the wind. I examined a few of these pieces on the 25th of the following April, and found nothing but larvæ another examination was made on the 12th of the following month, when nothing but larvæ were found, but all were dead.

scholarly journals NOTES ON THE EARLY STAGES OF CALOPTERON RETICULATUM, Fabr.

1883 ◽  
Vol 15 (5) ◽  
pp. 97-98
Author(s):  
D. W. Coquillett
Keyword(s):  
Outer Edge ◽  
Pale Yellow ◽  
Early Stages ◽  
Original Shape ◽  
Brown Color

On the 10th of July I found a pupa of this species suspended by the hind end of its body beneath a log. The 1arval skin was rent and worked backward, but still retained nearly its original shape and color, and by comparing it with certain larvæ which I have frequently met with in similar situations, there is no doubt in my mind but that these latter belong to the above species.These larvæ very closely resemble that figured by Packard on page 465 of his “Guide” (fig. 432), which in the text on the succeeding page is referred to Photuris. The dried specimens now before me measure about 12 mm., and are of a dull purplish-brown color; venter pale yellow, tinged with pink and marked with a brownish stripe on each outer edge, and with two rows of brown spots, these not extending upon the first three segments; head retractile, dull blackish, the region of the jaws polished brown, and furnished with four black prickles, the upper two of which are placed transversely, the lower two longitudinally.

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

Formation of Dislocation Channels in Neutron Irradiated Molybdenum

1972 ◽  
Vol 30 ◽  
pp. 672-673
Author(s):  
S. Mahajan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ambient Temperature ◽  
Room Temperature ◽  
Channel Formation ◽  
Early Stages ◽  
Transmission Electron ◽  
Three Stages ◽  
Two Stages ◽  
Polycrystalline Molybdenum

The evolution of dislocation channels in irradiated metals during deformation can be envisaged to occur in three stages: (i) formation of embryonic cluster free regions, (ii) growth of these regions into microscopically observable channels and (iii) termination of their growth due to the accumulation of dislocation damage. The first two stages are particularly intriguing, and we have attempted to follow the early stages of channel formation in polycrystalline molybdenum, irradiated to 5×1019 n. cm−2 (E > 1 Mev) at the reactor ambient temperature (∼ 60°C), using transmission electron microscopy. The irradiated samples were strained, at room temperature, up to the macroscopic yield point.Figure 1 illustrates the early stages of channel formation. The observations suggest that the cluster free regions, such as A, B and C, form in isolated packets, which could subsequently link-up to evolve a channel.

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