The cytology of oogenesis and fertilization in Korean pine (Pinus koraiensis Sieb.et Zucc.),has been investigated.The material on which these investigations were made was collected at Benxi County,Liaoning.The results are briefly summarized as follows: 1. Oogenesis After the gametophyte starts developing in the followingspring,the archegonial initials appear towards the end of May (1980).Then the nucleus of the archegonial initial comes to lie towards the upper end of the cell,the first division is followed by a transverse wall giving rise to the primary neck cell and the central cell.The neck cell divides by two vertical walls at right angles to each other resulting in four cells,which lie in a single tier.The central cell enlarges rapidly but as there is no corresponding increase in the amount of cytoplasm,numerous vacuoles are formed.Later the vacuoles tend to disappear and the cytoplasm becomes denser.Small globular structures appear,and occur singly or in groups of two or several.These are called "proteid vacuoles".The jacket cells surround the archegonium except in the neck region.In the middle of June, the nucleus of the central cell divides to form two nuclei separated by a phragmoplast.The wall laid down between them separates a small, lenticular ventral canal cell from the large egg cell.The ventral canal cell soon degenerates and only its remnants can be seen.The egg nucleus migrates towards the centre.While doing so it greatly increases in size. The archegonia are single,2(3—5) in number.The egg is elongatoellipsoidal,about 550—880×370—650μ in size,and its nucleus is large,140—200×110—170μ. 2. Fertilization,The pollen tube makes its way between the neck cells. Both the sperm nuclei along with the tube nucleus,stalk cell and cytoplasm are released inside the archegonium.The larger of the male gamates proceeds towards the egg nucleus,while the smaller along with the stalk nucleus generally remains in the upper part of the archegonium and ultimately disintegrates.The functional sperm nucleus becomes pressed against the egg nucleus.The fertilization took place about June 21—25 (1980).The essential process of the fusion of egg and sperm nuclei during syngamy could be outlined as follows:(1)the sperm nucleus made contact with the egg nucleus;(2) the fusion of nuclear membranes happened between the male and female nuclei;(3) the male and female chromatins condensed to form two separate groups of chromatic threads;(4) the male and female chromosomes grouped respectively in their own spindles;(5) then the two spindles fused together and all the chromosomes become arranged at equator of this broad spindle;(6)two daugter nuclei resulted from the mitotic division;(7) finally the neocytoplasm formed from the male and female cytoplasm. The ultrastructural features of the proteid vacuoles in egg cytoplasm, pattern of the fusion of male and female nuclei in fertilization and formation of the neocytoplasm during the first division of the zygote nucleus are also discussed in the present paper.

In the majority of cases,the dormancy of fruits of manchurian ash (Fraxinus mandshurica Rupr.)may be broken by the treatment of combination of warm and cold stratification,i.e.treatments of warm temperatures (20℃) for 4—5 months and then followed by cold temperatures (5℃) for 4—5 months.There are a number of causes in relation to the dormancy of these seeds,but the main ones are the incomplete development of the embryos and the restriction of the oxygen supply to the embryos by the enveloping layers of the endosperm,testa and pericarp.The action of the growth-inhibitiog substances in the pericarps may also take a part in this respect.At warm temperatures,the embryo undergoes rapidly growth within the imbibed fruit.The roles of low temperaturs are the increase of the intensity of anaerobic respiration of the embryos under oxygen deficient condition,decrease the requirement of oxygen for germination and the increase of the resistant force of the embryos to the action of inhibiting substances.Under the above indicated actions of warm and cold temperatures,the activity of the embryos are able to overcome the resistance of the enveloping membranes and ultimately the seeds germinate.

Laboratory tests with fungicides and field trials by spraying the carbendazol and bordeaux mixture in 1977—1980,were effective in control the olive leaf spot. Control tests showed that eradication the sourse of pathogen was important.Pruning in combination with fungicidal treatment had a good effect at 95.01—98.18%. In large scale trials,according to the incidence of the disease, integrated control using pruning in winter and interval spraying with carbendazol and bordeaux mixture in spring and autumn gave excellent control at 96.48—98.69%.

Stem rot of black locust (Robinia pseudoacacia) which caused high mortality of the trees has been observed in the most part of Jiangsu province since 1972.The pathogen attacks the trunk or roots of its host to induce a necrosis of inner bark usually around the basal or lower trunk.Some saprophytic sporodochia of Fusarivm sp.may be observed in cracks or diseased part of the bark.When a trunk was completely encircled,the tree wilted gradually. Isolation and inoculation experiments indicate that Phytophthora cinnamomi Rands is the pathogen of the disease.Infection occurs from March to October and mostly from May to September.Contaminated soils and infected plants are main sources of infection.

This paper has treated the forest fire as a combustion system.The values of every layer relate to the available energy (Joules) released in per unit volume (cubic meter) within the flaming front at the head of the fire. The paper assumes that the forest fire intensity comes from the two constributions——the burning rate and the mean burning acceleration,and can be expressed by the linear homogenous ordinary differential equation. This equation is considered as a basic dynamic equation to determine the forest fire intensity.Conclusion: (1) If the intensity of the forest fire does not exceed 1×10³KW/m² (i.e.the combusitible materials burned do not exceed 3kg/m³),it may be regarded as low intensity. (2) When the mass W₀ of the combustible materials,such as dead leaves,grass,various-sized twigs and so forth exceeds 3 kg/m³,no matter how fast or slow the spread rate of the fire is,the intensity must exceed 1×10³KW/m²,and it may be regarded as high intensity. (3) Generally,the intensity of the fire is proportional to the spread rate because the spread of the fire is exponentially increased by wind spread and decreased by moisture content of the combustible materials,so the high intensified forest fire usually occurs in drought areas or on strong windy days. (4) The fire going up slopes increases its rates of spread and intensity,becoming the phenomenon of "blow up" and so it is very dangerous for the firefighters to put it out in its front.On the contrary,the fire coming down slopes decreases its rate of spread and intensity and so it is safe for the firefighters to distinguish it. (5) According to the different elements,including the estimation of the fire starting energy,the moisture content of the combustible materials, the amount (W⁰) of the combustible materials of the surface and the wind speed,we can timely predict the fire behavior by the forest fire intensity so that we can thoroughly control and make use of the fire.

The physical and mechanical properties of the wood of Yunnan pine (Pinus yunnanensis Franch) were influenced adversely by the occurance of cross grain as the present investigation indicated.The effect on the shrinkage in radial and tangential directions as well as in volume was not very obvious until the slope of the cross grain exceeding 20%,and became rather serious at the grain slope of 50%.Along the grain,the effect of cross grain on shrinkage was found much more noticeable.The grain slope beyond 20% increasing every 10% led the coefficient of shrinkage along the grain enlarging by 71%.Thus,the occurance of cross grain may be supposed tobe the main cause of developing bow or spring in the process of seasoningof a board. The cross grain in wood of Yunnan pine affected its mechanicalproperties to a great extent.The compressive strength parallel to the graindecreased by 14% when the grain slope beyond 20% increased every 10%,and decreased by 45% at the grain slope of 50%. The influence of cross grain on static bending strength of a beam was also not very obvious at the grain slope less than 10%.It decreased only 10% at the grain slope of 10%.Beyond the grain slope of 20%,the strength decreased by 56% with the increasing grain slope every 10% and decreased by 77% at the grain slope of 50%.As regards its modulus of elasticity,it decreased by 10% (average value for green and air-dried specimen) at the grain slope of 10%.It decreased by 54% as the grain slope beyond 20% increasing every 10% and decreased by 79% at the grain slope of 50%. Further,the impact toughness decreased by 10% (average value for green and air-dried specimen) and by 65% at the grain slope of 10% and 50% respectively.

In accordance with the statistics,an efficient log sorting line may be consisted of 1—6 conveyors,of which the log sorting line with one conveyor accounts to 31 per cent,two conveyors 34.6 per cent and three convyors 21.9 per cent.Owing to lack scientific basis in practice,the length distribution of tandem conveyors in one sorting line is very complicated.This paper theoretically probes into the reasonable length distribution of some tandem conveyors and gives the calculating method. In order to discuss the length distribution of conveyors,the variational law of the occupied coefficient by logs in the sorting line should be studied.In accordance with the factfinding data,this paper gives the formula (1) for calculating the occupied coefficient (?) in any section of the sorting line expressed by the ratio α of the length distribution The principle for determining the length distribution is that the maximum chain pull of each conveyor should be equal.Thus,this paper gives the formula (14) for calculating the ratio (α₁)₂ of length distribution of the first conveyor in two tandem conveyors sorting line and the formula (23) for calculating the ratio (α₁)_n of the first conveyor in n conveyorsorting line.In the last part,the author of this paper gives the optimum seeking method for determining the type of conveyor,the size of chain and the length of tandem conveyors under the given length L of the log sorting line.