共查询到19条相似文献,搜索用时 62 毫秒
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本文分析了七级恒温和五组变温条件下白茨粗角萤叶甲(Diorhabda rybakowi Weise)的种群生长,组建了生命表.得知不同恒温与幼期存活率的关系呈二次曲线型变化;变温对幼期存活率的影响受其变幅大小的影响,23—31℃的变温有利于该虫的世代存活.成虫寿命和产卵量随试验温度上升分别呈现“S”形下降和二次曲线趋势;变温下成虫寿命延长,产卵量明显增高.采用Weibull函数模型能很好地模拟试验温度和温周期条件下种群世代死亡率的变化.在19—35℃恒温下,种群周限增长率可用二次曲线方程表示.在17.8—37.8℃种群生长为增长趋势.在变温下,种群周限增长率和变温的变幅呈负相关.在平均温度为27℃、变幅为25.1℃时,种群生长保持稳定. 相似文献
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自从1762年蚜虫孤雌生殖的现象被描术以后,直到十九世纪初方才证实了枝角类也同样进行这种生殖方法.后来经过Kerlherve氏(1892)与Smith氏(1915)进一步的研究,又确定在这类动物中孤雌生殖与两性生殖相互交替,发生所谓世代交替的现象。通常春、夏、秋三季进行孤雌生殖,雌体所产夏卵,不需要受精,即能发育;孵化出来的都是雌体。 相似文献
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涡虫异常生殖过程的观察 总被引:1,自引:0,他引:1
涡虫被异物穿插后,出现在咽前断裂的异常无性生殖,及其断裂形成的头部片段不能完全再生成一正常个体的情况。这一特殊现象,可以认为是异物穿插破坏了涡虫体内抑制生长物质正常梯度分布的结果。 相似文献
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大劣按蚊生殖营养周期的实验室观察 总被引:1,自引:0,他引:1
本文观察大劣按蚊的生殖营养周期。在实验条件下每只雌蚊一生平均产卵326.92个,其中有2只产卵900个以上,雌蚊寿命可达61天,有2只雌蚊吸血9次,完成8个生殖营养周期。 相似文献
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中国水蛇Enhydris chinensis (Gray)生殖周期与生殖型式的研究 总被引:3,自引:1,他引:3
中国水蛇于7月末8月初精子发生开始新的周期性复生,大部分为精母细胞。10—12月以至次年1月初大部分为成熟精子及变态中的精细胞,精子贮于附睾或输精管中过冬。11月至次年5月大部分输卵管中也存有精子。雌水蛇一年一次排卵,卵胎生。5月末至6月初见有蛇胚,孕妊期78—84天,8月中旬至9月中旬产仔蛇,每胎产仔6—21条。 相似文献
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HEATHER J. BROMLEY 《Zoologica scripta》1978,6(3):197-201
Laboratory studies on the normally fissiparous Dugesia biblica from Israel (3 n =27+ x supernumeraries) have been made in order to investigate fission rates and spontaneous maturation of four fissioning populations and one clone. Laboratory induced maturation in a sixth population of D. biblica resulted in the laying of fertile cocoons, the offspring of which were either 3 n =27+ x , 2 n = 18+ x or 2 n = 18+ x It is suggested that triploidy is primarily responsible for the lack of sexual reproduction in the field, and that unequal inheritance of supernumerary chromosomes during mitosis may explain the differing tendencies to undergo spontaneous maturation by individuals of a clone of D. biblica. The karyotype, habitat and reproduction of D. biblica is compared with a closely related but diploid, normally sexually reproducing Dugesia form and possible relationships between these two are discussed. 相似文献
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目的:探讨恒定磁场对日本三角涡虫(Dugesia japonica)无性横裂生殖及抗氧化酶活力的影响.方法:应用种群累积培养法,观察了恒定磁场对日本三角涡虫的种群增长、无性横裂生殖及涡虫体内超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活力的影响.结果:场强大小在200mT-500mT范围的恒定磁场能促进涡虫的无性横裂生殖,但恒定磁场显著抑制涡虫的SOD及CAT活力.结论:日本三角涡虫对恒定磁场的生理学响应较为敏感,可作为生物磁学研究适宜的实验材料. 相似文献
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日本三角涡虫的耗氧率和窒息点 总被引:1,自引:0,他引:1
应用静水呼吸室法,测定10℃、14℃、18℃、22℃、26℃和32℃温度下日本三角涡虫(Dugesiaj aponica)的耗氧率和窒息点,并测定涡虫耗氧率是否与温度和昼夜节律有关。结果表明,10℃和14℃涡虫耗氧率很低;18℃、26℃和32℃耗氧率较高;22℃涡虫耗氧率低于18℃、26℃和32℃条件下的耗氧率(P〈0,05)高于10℃和14℃条件下的耗氧率(P〈0.05)。18℃时窒息点最高,22℃窒息点最低。10℃、14℃、18℃、22℃、26℃和32℃温度下涡虫的窒息时间分别为125h,120h,55h,42h,37.5h和18.5h。18℃、22℃和26℃3个温度下涡虫耗氧率都呈昼夜节律性变化,白天耗氧率低,晚上耗氧率高(P〉0.05)。同一时间段比较,22℃耗氧率也最低。 相似文献
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Summary The submicroscopic structure of the nerve cells in the planarian brain was studied. Close similarities with neurons of other invertebrates were noted. In the cytoplasm of the planarian nerve cells there are at least three types of vesicular inclusions: 1) Clear vesicles (200–800 Å in epon embedded tissue) similar in morphological appearance to classical synaptic vesicles. These have generally some content of extremely low density but occasionally a dense core. 2) Dense vesicles (400–1,200 Å in epon embedded tissue) containing highly osmiophilic granules. Between the limiting membrane of the vesicle and the granule there is always a clear rim of variable width. These vesicles closely resemble synaptic vesicles described in vertebrate adrenergic endings. 3) Neurosecretory vesicles (600–1,300 Å in Vestopal embedded tissue) similar to elementary granules observed in neurosecretory systems in vertebrates and invertebrates. All three vesicle types have the same mode of origin from the Golgi membranes. All are present in the nerve cell processes of the neuropil as well as in the perikarya. Any given perikaryon or axon contains only one of the three vesicle types. All of these vesicles are considered to be discharged into the axons from their site of origin within the perikaryon. 相似文献
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James E. H. Sawyer 《BMJ (Clinical research ed.)》1903,2(2243):1630-1631
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John Grayson 《BMJ (Clinical research ed.)》1951,2(4744):1379-1382
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