. Contributions from the Botanical Laboratory, vol. 8. Botany; Botany. nnd covc^rs the advancing needle like a tent. It is evident from tlie move- ment of the granular mesoplasm that material foi' this cone and for the layer covering the needle is supplied by flow from other regions, but if the needle is pushed through far enough, particularly if it is moved I'apidly, this flow will be inadequate and a strain will result which may find relief in one of several diffe'rent ways. The plasmalemma may be ruptured, resulting in death of the cell. The protoplast may be completely punctui'iMl at the p
. Contributions from the Botanical Laboratory, vol. 8. Botany; Botany. nnd covc^rs the advancing needle like a tent. It is evident from tlie move- ment of the granular mesoplasm that material foi' this cone and for the layer covering the needle is supplied by flow from other regions, but if the needle is pushed through far enough, particularly if it is moved I'apidly, this flow will be inadequate and a strain will result which may find relief in one of several diffe'rent ways. The plasmalemma may be ruptured, resulting in death of the cell. The protoplast may be completely punctui'iMl at the point at which tlui needle enters and at the opposite side wluM'e the needlfi tip stretches it into the form of a cone. In this case the severed edges of the layer about the needle come into contact with the edges of the puncture in the cone and fuse. The protoplast resumes it normal contours, but a tube of protoplasm now surrounds the needle which joins the proto- plast at both ends (see Fig. 4). Periiaps the situation may be more clearly visualize(l by analogy with invertebrate em- bryology. The n(;edlr first invaginated th ,. can be follow(Ml. The hole grows slowly after its initial rapid lormatmn, and as it enlarges the t.^gether until finally only a ball of protoplasm remains, c( a nucleus l)ut uo cmtral vannde (Fig o) What is now the outer layer of this mass ci)nsists m part of the layer originally in contact with the cell sap. The cytoplasm is normal, the streaming of the graindes continues, and no swelling or appearamv of Brownian movement results. An enlarging puncture id' this sort mM inlnM|Uently arises at the point at which the needle first enters the protoplast, .u- more rarely. a. 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 University of Pennsylvania. Botanical Labo
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1892
