Regeneration / by Thomas Hunt Morgan.

  • Morgan, Thomas Hunt, 1866-1945.
Date:
1901
Catalogue details

Licence: Public Domain Mark

Credit: Regeneration / by Thomas Hunt Morgan. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    others may be without nuclei. The nucleated pieces produce a new- membrane, and later become typical organisms, but non-nucleated pieces do not form a new membrane, and soon disintegrate. Nuss- baum ('84, 'Z6) cut into pieces the ciliate infusoria, oxytricha and gastrostyla. Those pieces that contained a nucleus quickly regener- ated a new whole organism of smaller size, that had the power of further reproduction, while the pieces that did not contain a part of the nucleus showed no evidence of regeneration; and, although they continued to move about for as much as two days, they subse- quently disintegrated. Gruber obtained the same result on another ciliate infusorian, Stentor coBvuleus. He found that, although the non-nucleated pieces close over the cut-surface, and move about for some time, they eventually die. He further showed that a non- nucleated piece containing a portion of a new peristome in process of formation will continue to develop this new peristome, although a new peristome is never produced by a non-nucleated piece under other circumstances. He believes that if the new peristome has begun to be formed under the influence of the old nucleus, it may continue its development after the piece is severed from its connection with the nucleus. A non-nucleated piece containing a part of the old peristome does not produce a new peristome from the old piece. Gruber observed that a non-nucleated piece of amoeba behaves differ- ently from a nucleated piece, and dies after a time. Klebs found that when certain algae are put into a solution that does not seriously injure them, but causes the protoplasm to contract into balls, some of these contain nuclei, others not. If, for instance, threads of zygnema, or of spirogyra, are placed in a 16 per cent solu- tion of sugar, the protoplasm of each cell breaks up into one or more clumps, some with nuclei, others without. Both kinds may remain alive for a time; some of the non-nucleated pieces may live for even six weeks. The nucleated pieces surround themselves at once, when returned to water, with a new cellulose wall, but the non-nucle- ated pieces remain naked. The latter can, nevertheless, produce in the sunlight new starch that is used up in the dark and is made anew on the return to light.^ Balbiani ('88) found that non-nucleated pieces of cytrostomum, trachelus, and protodon failed to regenerate, and Verworn ('89 and '92) obtained similar results on several other protozoa. Similar facts have been made out by Hofer ('89), Haberlandt and Gerassi- moff ('90). Palla ('90) found that in certain cases non-nucleated pieces, especially those from cells in growing regions, can produce a new cell wall; while more recently Townsend ('97) has shown in 1 In other plants, fumaria, for example, non-nucleated pieces do not seem to be able to make new starch after using up that which they contain at first.