CINEMATIC OBSERVATIONS ON THE GROWTH AND DIVISION OF CHLOROPLASTS IN NITELLA

As it elongates from about 0.2 to 80 mm, the Nitella internodal cell shows an increase in plastid number from a few thousand to about 4 million. The increase takes place by plastid division. A continuous motion picture record followed a population of 8 plastids in an elongating cell until their progeny numbered 18, a span longer than 1 fission cycle for some of the plastids. One complete fission-fission cycle was about 22 hr. The highly directed nature of chloroplast expansion (elongation) is lost when cell wall strain (expansion) is mechanically inhibited by pressing the cell between glass plates. The plastids then expand about equally in all directions in the plane of the cell surface. When a new direction of maximum strain is introduced by the mechanical induction of a lateral in the cell, the plastids elongate in this new direction. The direction of the protoplasmic stream does not show this striking response to strain but tends to follow the lines of the chloroplast chains, not the long axis of individual plastids.     

FURTHER OBSERVATIONS ON GROWTH OF SINGLE CELLS OF COCCOID BLUE-GREEN ALGAE

Initiation of growth (lag) and subsequent growth to visible colonies was examined for single cells of several coccoid blue-nreen algae under controlled incuba-tion conditions. At 30 or 39 C, with tungsten or fluorescent illumination, organisms such as Agmenel-lum quadruplicatum, strains PR-6 and strain BG-J, showed no evidence of lag associated with initiation of growth. The final colony count was within 20% of the expected number derived from cell counts and serial dilutions. For Anacystis nidulnns, Tx 20, a new medium C, 10 with EDTA as chelator was developed. In this medium groiuth of single cells at 39 C was excellent with quantitative recovery and no evidence of lag. At 30 C, however, Tx 20 showed anomalous behavior, lag and nonquantitative cell recovery. This behavior at 30 C is not yet understood.     

鸭绿江唇仔、稚鱼形态发育与早期生长

通过观察、拍照和测量的方法对鸭绿江唇(Hemibarbus labeo)仔、稚鱼的形态发育和早期生长进行了研究。结果表明:在19.6—25.8℃的试验条件下,唇初孵化仔鱼全长为(7.92±0.29)mm,2日龄头部两侧出现感觉芽;3日龄鳔一室原基形成,5日龄红色的脾出现,且仔鱼开口;7日龄卵黄囊吸收完毕,9日龄脊索末端开始向上弯曲;10日龄鳔二室形成,14日龄脊索弯曲完成,尾鳍边缘开始内凹;32日龄鳞片开始出现在鳃盖后缘的体表,同时各鳍发育完全,个体发育进入稚鱼期,43日龄全身被鳞,个体发育进入幼鱼期。根据卵黄囊、脊索和鳞片的变化,唇胚后发育可细分为卵黄囊期(0—6日龄)、弯曲前期(7—9日龄)、弯曲期(10—14日龄)、弯曲后期(15—32日龄)和稚鱼期(33—43日龄)。试验期间,全长和体质量的特定生长率分别为3.32%和12.16%;卵黄囊体积(V)与日龄(d)的关系为V=0.0048d3–0.0309d2–0.1240d+0.8453(R2=0.8933);全长(LT)、体质量(W)与日龄均为指数函数关系,相关方程分别为:LT=8.3821e0.0329d(R2=0.9586),W=0.0048e0.0969d(R2=0.9463);头长(LH)、体高(HB)的生长方程分别为:LH=–6E–05d3+0.002d2+0.1733d+0.7862(R2=0.9577),HB=–5E–05d3+0.0039d2+0.017d+0.9389(R2=0.9621)。     

齐口裂腹鱼耳石早期生长发育与日轮特征研究

文章研究了在实验室条件下齐口裂腹鱼仔稚鱼耳石早期形态发育与生长特点、第一轮纹出现时间和轮纹沉积规律。结果表明: 在13.5-17.2℃孵化条件下,微耳石和矢耳石在出膜前形成,而星耳石于出膜后第12天出现。在仔稚鱼生长过程中,微耳石由近圆形发育成贻贝形,矢耳石经历近圆形、锲形后发育为箭矢状,星耳石形状由近圆形发育为星芒状。微耳石的前区、背区和腹区及矢耳石的背区和腹区生长呈幂函数关系,而微耳石的后区、矢耳石前区和后区生长以及两对耳石的前后区半径之和与全长均呈线性相关。在(18.50.5)℃和(15.61.1)℃条件下,50%矢耳石样本第一轮纹均在出膜后第 2 天形成(分别为出膜后18h和19h),以后每天形成一轮。微耳石和矢耳石轮纹数均与日龄呈线性相关,方程斜率均与1差异不显著(P0.05),表明两对耳石的轮纹沉积均为日周期性。这些结果为研究齐口裂腹鱼野生种群繁殖期和早期生活史特征等生态学问题提供了重要依据。     

PRELIMINARY OBSERVATIONS ON THE GROWTH OF TRANSPLANTEDPELTIGERA CANINAUNDER SEMI-NATURAL CONDITIONS

Peltigera caninathalli have been successfully transplanted onto soil in a garden and in flowerpots. Garden samples showed marked seasonality and achieved growth rates of 6·4 cm per year. Pot-grown samples showed variation in the growth of individual thallus lobes and established that, under different soil hydration regimes, permanently hydrated thalli could sustain considerable linear growth rates for at least 140 days.     

GROWTH IN MEDEOLA VIRGINIANA CLONES I. FIELD OBSERVATIONS

The pattern of clonal growth in Medeola virginiana was mapped over twelve square meters in a successional white pine forest of eastern Massachusetts. From these maps and an additional sample of excavated plants, the distances and angles of divergence of daughter ramets from the base of the parent shoot were measured for 213 plants. All clonal growth parameters were found to be highly variable in the ñeld, with coefficients of variation ranging from 17–92%. The rules describing the pattern of growth of daughter ramets were found to be considerably more complicated than previously reported (Bell, 1974). The mortality of tubers, the natural variation of parameters of growth, and the complex patterns of daughter production all call into question the ability of idealized, deterministic models of growth to predict the form of clones and the position of ramets in the field.     

乌桕果实生长发育的观察及其营养物质积累的分析

<正> 乌桕(Sapium sebiferum(L. )Roxb. )是我国南方分布和栽培较广的油料树种。乌桕种子含有丰富的油脂,其油脂是重要的化工源料和传统的出口商品。如能掌握乌桕果实的生长发育及油脂物质积累规律,在生产上,可根据不同生长发育阶段采取相应的技术措施,以达到增产的目的。 为此,我们从1979年开始对乌桕果实进行定期观测和采样分析。现将试验结果,作简要的报道,供有关方面参考。     

臭氧对墨西哥豆瓢虫取食和生长的影响

本文报道在美国农业研究中心用臭氧在室内熏蒸和田间开顶熏蒸植物,用此饲养墨西哥豆瓢虫的实验,以及熏蒸后植物体内某些化合物含量变化的测定.结果表明,墨西哥豆瓢虫(Epilachna varivestis Mulsant)喜食臭氧(O₃)污染的植物,幼虫取食O₃污染植物后蛹显著重于取食未受污染植物所形成的蛹.根据豆瓢虫食性和植物体内糖含量的测定,可以认为,低浓度O₃污染导致植物体内糖含量的增加,是促使豆瓢虫取食量和蛹重增加的重要因素.