This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1870 Excerpt: ...then, how is the new matter produced? Does it take place by deposition upon the external surface of the investing membrane, or is the new matter produced by the soft formless matter in the interior? To put the question still more simply, Is the capsule, the so-called cell wall, formed by deposition of matter from the ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1870 Excerpt: ...then, how is the new matter produced? Does it take place by deposition upon the external surface of the investing membrane, or is the new matter produced by the soft formless matter in the interior? To put the question still more simply, Is the capsule, the so-called cell wall, formed by deposition of matter from the fluid surrounding it, or is it formed from within? and which is the oldest part of the capsule, its external or internal surface? If the new matter were deposited upon the external surface, we should expect to find that the membrane would become thicker and thicker as the growth of the organism advanced, while the central portion would remain unaltered. This, however, is not the case; on the contrary, we find that as growth proceeds, the wall in most cases becomes considerably thinned. It is clear, therefore, that the increase in size cannot be due to deposition from without. The matter deposited upon the inner surface of the capsule is always softer than its general substance, and the external surface of old capsules is cracked and ragged. In many of the algae this external surface serves as a nidus for the development and growth of smaller algae--a fact which clearly shows it has ceased to be active, is undergoing disintegration, and becoming fitted for the pabulum of other things, and is no longer capable of resisting the action of external conditions. This is the oldest part of the capsule which is now undergoing decay, and the small algae are living in part upon the products thus produced. The new material is added upon the inner surface of the capsule, layer after layer, and where there are several layers the innermost is the youngest and the outermost the oldest portion of the structure. If this be so, it follows that the inanimate mater...
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