猪冠状动脉的解剖学观察

本文对50例健康的商品猪心脏的铸型标本进行了观察,结果如下:左冠状动脉旋枝与锥旁室间枝的夹角为74.4±2.07度。对角枝出现率为24％,并证明了对角枝出现率与其夹角大小呈正比关系。窦房结枝84％来自右冠状动脉。房室结枝98％来自右冠状动脉。左房旋枝出现率为8％。室间隔的供血由锥旁室间枝的分枝负担61％,约为3/5,窦下室间枝的分技负担39％,约为2/5。室上嵴技、Kugel动脉、室间隔中枝和室间隔背倒前枝的出现率分别为78％、20％、68％和28％。心尖区的血液由左、右冠状动脉共同供应。50例左、右冠状动脉始部外径之比为1.2∶1。左、右冠状动脉在心膈面的分布类型以右强型为主。本文还讨论了猪冠状动脉与狗、人冠状动脉的异同。     

云南及邻近地区竹亚科增补

报道了云南竹亚科新记录２种,即冷箭竹和西藏香竹,归并了５个种名,它们是Ｃｈｉｍｏｎｏｃａｌａｍｕｓ ｔｏｒｔｕｏｓｕｓ Ｈｓｕｅｈ ｅｔ Ｙｉ,Ｄｅｎｄｒｏｃａｌａｍｕｓ ｆａｃｔｉｔｕｓ Ｙｉ,Ｃｈｉｍｏｎｏｂａｍｂｕｓａ ｙｕｎｎｎｅｎｓｉｓ Ｈｓｕｅｈ ｅｔ Ｗ．ｐ．Ｚｈａｎｇ,Ｃｈｉｍｏｎｏｂａｍｂｕｓａ ｎｅｐｏｕｒｐｕｒｅａ Ｙｉ,Ｆｅｒｒｏｃａｌａｍｕｓ ｒｉｍｏｓｉｖａｇｉｎｕｓ     

COUNTERFEIT HYBRIDS BETWEEN TRIPSACUM AND ZEA (GRAMINEAE)

Diploid (2n = 36) Tripsacum australe Cutler and Anderson var. hirsutum de Wet and Timothy, T. cundinamarce de Wet and Timothy, T. dactyloides (L.) L. var. dactyloides and var. meridonale de Wet and Timothy, and T. laxum Nash were crossed with Zea mays L. (2n = 20) as the pollen parent. True hybrids combine the cytologically nonreduced genome of Tripsacum (36 chromosomes) with the haploid (10 chromosomes) or more rarely diploid (20 chromosome) genome of Zea. Maternal offspring with 2n = 36 Tripsacum chromosomes commonly result from parthenogenetic development of cytologically nonreduced eggs. Some individuals with 2n = 36 Tripsacum chromosomes, however, resemble true hybrids in phenotype. These counterfeit hybrids incorporated Zea genetic material into their Tripsacum genomes without true fertilization having taken place. Offspring of counterfeit hybrids that were grown to maturity resembled their mothers in phenotype, and must have originated parthenogenetically. It is proposed that counterfeit hybrids are also produced in nature, and that this process contributes to origins of variation in gametophytic apomicts, and perhaps also in sexually reproducing species.     

MORPHOLOGICAL AND CYTOLOGICAL VARIABILITY IN TRIPSACUM DACTYLOIDES (GRAMINEAE)

A total of 235 accessions of Tripsacum dactyloides (L.) L. representing natural populations from 88 locations distributed throughout ten states of the United States were collected in the wild and studied morphologically and cytologically. Multivariate analysis of variance (MANOVA) was applied to 17 morphological characters recorded for 868 specimens from the 88 locations, which were further combined into 25 groups to facilitate analysis. Multivariate F ratios for six comparisons involving different groups were highly significant, indicating that the populations were significantly different on the basis of all 17 characters. Non-significant MANOVA F ratios for two comparisons between sympatric diploid and polyploid accessions showed them to be morphologically similar. Discriminant function (DF) analysis was employed to determine which characters contributed towards group discrimination. No one variable was found to distinguish between groups; rather, a combination of characters was necessary, and the combination changed with each comparison. Accessions were mainly either diploid (2n = 36) or tetraploid (2n = 72), with two triploids (2n = 54) reported from separate locations in Texas. Cytological data revealed that diploids and tetraploids occupy a more sympatric distribution than previously supposed. Morphological analysis suggested that diploids could not always be distinguished from polyploids on the basis of morphology alone, unless the appropriate characters were used. Information from cytological and morphological data showed Tripsacum dactyloides to be composed of many populations covering a wide range of variability, with each population possessing a characteristic combination of morphological attributes. It was concluded that T. dactyloides can be most meaningfully analyzed in terms of particular geographic regions, rather than attempting to elucidate natural relationships by correlating data from the entire United States.     

OBSERVATIONS AND EXPERIMENTS ON THE HESSIAN FLY (MAYETIOLA DESTRUCTOR SAY)

Experiments showed that a stem midge collected locally on couch grass ( Agropyron repens ) and similar midges collected on wheat, barley and rye were of the same species, i. e. the hessian fly, Mayetiola destructor Say. There were three main flights per year, with some overlapping of the generations. In experiments, Aegilops ovata, Triticum compactum, T. dicoccoides, T. durum, T. spelta and T. turgidum were successfully used as host plants besides wheat, barley, rye and couch grass. Individual female midges when moved from plant to plant gave rise to families on the different host plants; similarly, succeeding generations of midges were able to breed on various host plants other than those from which they themselves were reared. Oviposition also took place on plants on which larvae failed to establish themselves.
Wheat seemed more favourable for the hessian fly than couch grass, and more midges were reared from young plants than from mature ones.
Unisexual families occurred in about half the experiments. The following parasites were bred: Trichacis didas Walker, Eupteromalus? hemipterus Walker, Platygaster sp., Chrysocharis sp. and Tetrastichus sp.     

TISSUE CULTURE AND REGENERATION OF DISTICHLIS SPICATA (GRAMINEAE)

Distichlis spicata tissue cultures were initiated from mature seeds. Cultures displayed regenerable callus that was compact, white, and streaked with purple and green. Selection of compact areas at subculture established long-term, regenerable cultures. Removal of auxin and inclusion of 1 mg 1^–1 BA in the maintenance media induced regeneration. Histological sections indicate that although cells were typical of embryogenic types, regeneration was by shoot organogenesis. Regenerated plants flowered and set seed under field conditions.     

CHROMOSOMAL AND FLOWERING CHARACTERISTICS IN DWARF MISTLETOES (ARCEUTHOBIUM)

Chromosome numbers and other karyological features of Arceuthobium are reported for all species and subspecific groups in the United States and 7 of the 13 entities occurring in Mexico. The only chromosome number known in the genus is n =14 and the karyotype appears to be fundamentally symmetrical. The bivalents are significantly smaller than in the related genus Phoradendron. No supernumerary chromosomes, sometimes present in Phoradendron, were observed in Arceuthobium. The existence of strong isolating mechanisms, which apparently preclude natural hybridization, is advanced as a possible explanation for the absence of polyploidy in the dwarf mistletoes. The flowering characteristics of the American species are analyzed and classified into three principal groups: (1) winter and early spring flowering species with southern distributions, (2) summer flowering species with more northerly distributions, and (3) spring flowering species with the highest latitudinal distributions, but which essentially complete floral development during the previous summer. A fourth group is intermediate between the first and second categories.     

绞股蓝属的染色体研究

报道了葫芦科绞股蓝属（Ｇｙｎｏｓｔｅｍｍａ Ｂ１．）８种共２０个居群的染色体数目,分别为２ｎ＝２２,３３,４４,６６,８８多倍体现象极为普遍。两个亚属;绞股蓝亚属（Ｓｕｂｇｅｎ．Ｇｙｎｏｓｔｅｍｍａ）和喙果藤亚属（Ｓｕｂｇｅｎ．Ｔｒｉｏｓｔｅｌｌｕｍ）的染色体基数均为Ｘ＝１１,并结合该属植物形态特征、繁殖方式和地理分布,对普遍出现的多倍体现象进行了讨论。     

云南盘鳇消化系统解剖学、组织学及消化酶活性研究

采用形态学、组织学及酶学方法对云南盘逗(Discogobio yunnanensis)成体消化系统进行研究。结果表明, 云南盘逗消化系统有以下特征: 口下位, 口腔上皮分布有较多味蕾及杯状细胞, 食道粗大, 含有大量黏液细胞, 无胃, 肠道较长, 盘旋于体腔中, 成鱼盘旋10回, 肠道系数为5.06±0.61, 肠分为前中后三段, 肠腔中密布肠绒毛。消化腺为肝胰脏, 肝脏分为左右两叶, 胰脏弥散分布在肝脏中。消化系统不同部位消化酶活性大小不同, 脂肪酶活性: 肝胰脏>前肠>中肠>后肠, 胰蛋白酶、淀粉酶、碱性磷酸酶活性: 前肠>中肠>肝胰脏>后肠。云南盘逗口下位, 食道粗短, 肠道细长, 肠绒毛丰富, 肠道含较高的胰蛋白酶和淀粉酶活性, 消化系统所具有的这些特征与其以固着藻类为食有关。     

RESOURCE ALLOCATION AND REPRODUCTION IN POPULATIONS OF AMPHICARPUM PURSHII (GRAMINEAE)

Five New Jersey populations of Amphicarpum purshii (an annual panicoid grass) were investigated as to total allocation of biomass to reproduction and its distribution between aerial chasmogamous and subterranean cleistogamous inflorescences. Germination of both types of seed was documented, for the first time, in not only the field but under three laboratory temperature regimes. Overall, approximately 29 % of the shoot biomass was allocated to reproduction. On a population basis, subterranean inflorescences accounted for 37–100 % of the reproductive biomass, and these seed (5 × heavier but fewer in number) were the source of most surviving seedlings. Subterranean spikelets contained caryopses significantly more frequently than aerial spikelets. The ratio of the number of viable aerial seed to the number of viable subterranean seed increased from 0/4 to 4/2 with recentness and/or frequency of disturbance. As a pioneer species in secondary succession, Amphicarpum purshii produces a larger subterranean propagule, with greater seedling vigor and a higher probability of local reproductive success, and also a smaller aerial propagule in larger numbers with potentially greater genetic variability.     

"植硅体"含义和禾本科植硅体的分类

针对国内文献中对英文“Phytolith”等词语的中文译名呈多样化现象,建议统一用“植硅体”来涵盖之,其含义包括“Opal phytolith”和“Silica bodies”等,代表一门新兴学科,即植硅体学,已有的禾本科植硅体分类中,不同学者采用了各自不同的分类规则和术语,本文通过分析,对比现有禾本科植硅体不同的分类方案,以期对其分类系统的研究现状和所存在问题提出看法,有利于今后深入研究。     

OBSERVATIONS ON ROOT-PARASITISM IN CORDYLANTHUS (SCROPHULARIACEAE)

Eight species of Cordylanthus (Scrophulariaeeae: tribe Euphrasieae) representing the three major sections of the genus were successfully grown both with and without a host plant, demonstrating that the plants are facultative hemi-parasites capable of completing their life cycle without a host under the favorable conditions of greenhouse culture. The plants are almost certainly parasitic in the wild. Even though haustorial connections were formed by Cordylanthus on the roots of all host plants provided, most species were more vigorous when growing with certain hosts (Quercus, Pinus, Helianthus) than with others (Plantago, Phleum). This indicates a difference in the ability of the parasite to obtain materials successfully from the various plants used as hosts. Natural hosts are inferred for 15 species of Cordylanthus from the presence of associated species in nature. The haustoria are exogenous in origin, being formed by dedifferentiation of several cells in the hypo-dermal or subhypodermal layers of the rootlets. Anatomically the haustoria differ from those reported for other members of Euphrasieae in having secondary vascular structure and abundant connecting strands. The vascular structure of haustoria is composed mainly of specialized vessel elements. Root-parasitism gives Cordylanthus the ability to grow in arid areas during the summer after most other annuals have died, thus successfully equipping the plants for survival and expansion in western North America.     

EPIDERMAL FEATURES AND SILICA DEPOSITION IN LEMMAS AND AWNS OF ZIZANIA (GRAMINEAE)

In four species of Zizania (Gramineae: Oryzeae) epidermal features of pistillate and staminate lemmas, paleas, and awns were studied by scanning electron microscopy (SEM) and energy dispersive X-ray analysis. Features observed were silica bodies, siliceous papillae, pitted siliceous papillae, stomata, microhairs, and prickle hairs. Staminate lemmas have all of these features. Pistillate lemmas have silica bodies and prickle hairs, lack stomata, and differ among species in occurrences of microhairs and siliceous papillae and pitted siliceous papillae. Awns of pistillate lemmas have silica bodies, prickle hairs, microhairs, and stomata; therefore, they possess a more complete set of features than their attached lemmas. Shapes of silica bodies on pistillate lemmas differ among species. A taxonomic key based on SEM observation of pistillate lemmas separates the four species by the shapes of silica bodies, arrangement of prickle hairs, and occurrences of microhairs and siliceous papillae. The main silica-containing structures are silica bodies, siliceous papillae, pitted siliceous papillae, and to a lesser extent prickle hairs. Pitted siliceous papillae with circular raised rims are formed by collapse or exfoliation of the tops of siliceous papillae; these have not been previously described in grasses. Comparison of epidermal features in the lemmas and leaves of Zizania shows that the former lack three kinds of nonsilicified papillae and epicuticular wax that are present on the latter but the lemmas have siliceous papillae and pits that are absent in leaves.