PHOTOPERIODISM IN AMARANTHUS CAUDATUS. I. A RE-EXAMINATION OF THE PHOTOPERIODIC RESPONSE

Zabka , George G. (State U. Iowa, Iowa City.) Photoperiodism in Amaranthus caudatus. I. A re-examination of the photoperiodic response. Amer. Jour. Bot. 48(1): 21–28. Illus. 1961.—Under the conditions described in this study, Amaranthus caudatus is not subject to inductive short days until it has reached its “sensitive period” or age which is approximately 30 days after the time of germination. Beyond this sensitive period, 2 days are sufficient to initiate inflorescence primordia. Macroscopic identification of this response is possible 2–3 days later, if the plants are retained on short photoperiods. Continued development of the inflorescence is also promoted by short days. This species will also initiate inflorescence primordia on long days of 18 hours duration approximately 60 days beyond germination. Consequently, this is not an obligate short-day plant as previously described. Although A. caudatus will initiate primordia on long days, subsequent normal development of the inflorescence proceeds only under short photoperiods. Plants initiating primordia on long or short photoperiods and then placed on long photoperiods will produce inflorescences which are stubby, generally recurved and spread at the apices. Subsequent flowering and seeding is also delayed. Plants initiating primordia on long days and then placed on short days develop mature inflorescences rapidly but they are divided at the apices and exhibit numerous basal branches.     

EXPERIMENTS ON THE PHOTOPERIODIC RESPONSE IN PINEAPPLE

Gowing , Donald P. (Pineapple Research Institute of Hawaii, Honolulu.) Experiments on the photoperiodic response in pineapple. Amer. Jour. Bot. 48(1): 16–21. 1961.—The initiation of flowering of ‘Smooth Cayenne’ pineapple plants is neither strictly a response to photoperiod (day lengths of 10 hr. 51 min.–13 hr. 24 min.) nor to a minimum temperature (minima from 50° to 72°F. in different areas) under natural Hawaiian conditions. Depending on the kind of planting material used and the time of planting, natural initiation of flowering may take place any month of the year. Slips planted in the fall generally initiate flowering in December of the following year. However, exposure of an 8-mo.-old slip-planting to a day length of 8 hours for 40 days starting Sept. 8 induced flowering irrespective of night temperatures from about 60 to 80°F. Interruption of the dark period by illumination at 30 ft.-c. from midnight to 1 a.m. suppressed the inductive effect. Lowering the night temperature to 60°F. was, of itself, non-inductive. Field-grown, 11-mo.-old plants treated in place responded similarly, in that 25 periods of 8-hr. day length starting Sept. 5 induced 60% of the plants to flower, and the night illumination suppressed the inductive effect as before. Daily application of 0.12 mg. of the major native pineapple auxin (indole-3-acetic acid) at the beginning of the dark period had no detectable effect on the short-day treatment, and similar application of an antiauxin (4-chlorophenoxyisobutyric acid) did not affect the suppression of flowering by the light-break. Supplemental illumination of field-grown 12-mo. plants to provide a photoperiod of more than 15 hr. daily from Nov. 4 to Jan. 30 did not suppress the natural initiation of flowering which occurred in early December (day length about 10 hr. 50 min.). ‘Smooth Cayenne’ pineapple is therefore a quantitative, but not an obligate, short-day plant.     

中国境内始舌齿鱼(Eohiodon)的发现——兼论骨舌鱼类的分布

本文记述了产自苏北沭阳阜宁群上部的一始舌齿鱼,依据它在外形、鼻骨及尾部结构上与始舌齿鱼现有种的区别,将它定为一新种:沭阳始舌齿鱼(Eohiodon shuyangensis ,sp.nov.)。同时,本文对骨舌鱼类的历史动物地理学问题作了尝试性的分析。     

马占相思林冠蜘蛛群落的结构分析

用杀灭菊酯喷洒林冠,收集得蜘蛛２６种,１９９只。群落组成以不结网为为主,全年均保持较高数量水平。结网类从４月至１０月成指数曲数下降。４个相似样地上的群落结构显著差异。以ＭａｃＡｒｔｈａｒ分布模型为基础,求出每个种在群落中的数量－时间－空间的重要值。结果以斜蛛的ＮＴＤ为最,斑络新妇幼体为次。蜘蛛－昆虫群落的营养结构在各样地上是一致的。蜘蛛作为捕食者,占总数１２－１５％。     

A STUDY OF THE STRUCTURE AND DISTRIBUTION OF THE NEXUS

Nexuses, that is, fusions of plasma membranes of adjacent cells, are described in mammalian smooth and cardiac muscle, median giant axon of earthworm, frog skin, and rat submandibular gland. In smooth muscle they usually occur where a process from one cell either meets a process of, or projects into a neighboring cell. On the other hand, in mammalian heart muscle and in earthworm giant axon the nexuses occur along the intercalated disc and intercellular segmental septa, respectively. Their occurrence between these excitable cells is correlated with propagation of action potentials by an electrical rather than chemical mechanism. Since the nexuses may offer pathways for electric current between cell interiors, it seems possible that they constitute a link in the structural basis for electrical transmission in these systems. In epithelia, nexuses usually appear as part of a terminal bar complex. This is true in the rat salivary gland studied here. In the epidermis of frog skin, nexuses are less numerous between the basilar columnar cells than between the subjacent squamous cells. The nexuses which occur in epithelia in frog skin and rat salivary gland are distributed as though to provide seals against electrochemical backleaks and sites of chemical exchange between cell interiors.     

FROM NAUGHTY GOODS TO NICOLE MILLER: MEDICINE AND THE MARKETING OF AMERICAN CONTRACEPTIVES

In the rich history of modern pharmaceutical advertising in the United States, few medical objects have been as controversial as contraceptives. Condemned in the 1870s as lascivious devices whose commercial visibility would tarnish female sexual purity, contraceptives have in the late twentieth century been repackaged by pharmaceutical companies as the smart, progressive, and fashion-conscious woman’s ally. This article explores evolving perspectives on the place of birth control in public spaces from the mid-nineteenth century to the present. In so doing, it elucidates the changes and continuities in the long and contested history of marketing, medicine, sexuality, and reproductive control.