DIFFERENTIATION IN HYDROID COLONIES. II. AGLAOPHENIA
DIFFERENTIATION IN HYDROID COLONIES. II. AGLAOPHENIA
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Hydroid 集落的分化。
DOI：
10.2307/1536100
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发表时间：
1910
期刊：
影响因子：
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通讯作者：
H. B. Torrey
中科院分区：
文献类型：
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作者：
H. B. Torrey
在以前的一篇论文中，我提请注意这样一个事实，即许多水螅虫物种的结构类型随着年龄的增长而变化，也就是说，在它们的生长方向上。“茎近端直的可能在远端弯曲。在殖民地发展的早期阶段交替出现的比朗什，后来可能成对出现。水鞘花梗的长度和环纹，水鞘的大小、比例和排列也同样随距茎基部或分支的距离而变化。”试图分析这些事实所暗示的分化问题开始了，在一个特别适合实验的钟形藻物种上。所得到的结果支持这样一种观点，即群体中个体分化的渐进变化并不取决于外部条件的变化，而是取决于内部条件的变化;这些变化具有生理特征，并不导致形态决定因素或残余生殖质的概念。也有人提出这些事实对衰老问题的影响。因为，在具有聚伞花序类型的芽的水螅体如Caimpanularia的茎上，个体作为连续的世代出现，形成，同时，整个群体的一部分。因此，任何两个个体的比较都可能显示出它们结构上的差异，这在某种程度上对应于殖民地中与它们年龄差异相等的生理变化时期。自从这些结果发表以来，出现了几篇重要的论文，对自然死亡和发展的关系表达了截然不同的观点。迈诺特（Pop. Sc. Mo.，11月，I907，第472页）认为，随着细胞分化，它们会失去一些生存能力。洛布（Pfluger's Arch）I24，1908，p. 41 I），在陈述这个结论在化学术语如下：UUniv.加州公共图书馆，Zo6logy，2，p. 323.
In a former paperr I called attention to the fact that many species of hydroids change their structural type with age, that is, in the direction of their growth. "Stems straight proximally may become sinuous distally. Biranches which alternate during the early stages of colonial development may later originate in pairs. Length and annulation of hydrothecal pedicels, size, proportions and ornamentation of hydrothecae may similarly vary with the distance from the base of stem or branch." An attempt to analyze the problems in differentiation suggested by these facts was begun, upon a species of campanularian peculiarly well adapted for experimentation. The results reached favored the view that the progressive changes in the differentiation of the individuals of a colony are not dependent upon changes of external conditions, but upon changes of internal conditions; and that these changes are of a physiological character, and do not lead to a conception of morphological determinants or residual germ plasim. The bearing of the facts upon the problem of senescence was also suggested. For, on the stem of such a hydroid as Caimpanulariawith a cymose type of budding-the individuals appear as successive generations, forming, at the same time, parts of the whole colony. Accordingly, a comparison of any two individuals might be expected to show a difference in their structure corresponding in some degree to a period of physiological change in the colony equal to their difference in age. Since the publication of these results, several important papers have appeared expressing radically different views on the relation of natural death and development. Minot (Pop. Sc. Mo., Nov., I907, p. 472) holds that as cells differentiate they lose something of their capacity to live. Loeb (Pfluger's Arch., I24, 1908, p. 41 I), after stating this conclusion in chemical terms as follows: UUniv. Cal. Publ., Zo6logy, 2, p. 323.