Mosquitoes and tyres

Car tyres not only help people to move about, they also assist exotic mosquitoes in travelling thousands of miles around the world to colonise new areas. The remarkable adaptability of mosquitoes that has led to their enormous success in the past can be seen close to home.     

Algae on the internet

Increasingly electronic communication and a variety of electronic resources are accessible to a larger group of people within the scientific community. This paper outlines the range of resources that are available, and comments on their current and future value to the phycological community. Resources discussed include mailing lists and newsgroups. These are useful tools for rapid, informal, targeted communication, although the technology employed places limitations on the type and format of information which may be distributed. The World Wide Web (WWW) has the potential to overcome these limitations, the quality, complexity and value to the phycological community of the sites on the WWW are extremely variable, with some material being of dubious quality. However, it is possible to access high quality resources including culture collection catalogues, high quality images and microbial and molecular databases. As well as some of the current resources, this paper discusses some possible directions for the future of phycology on the internet.http://wiua.nwi.ac.uk/     

四川地区几种常见蚊虫越冬情况的观察

1953—1957年我们曾在四川地区对几种常见蚊虫的越冬情况作了一些观察,现将所得结果简述如下: 1.中华按蚊 A.hyrcanus var.sinensis Wied. 中华按蚊孳生地很广,遍及省内各地。主要为水田最多,池塘、沼泽、沟渠等处次之。从九个     

Polymorphic snails on varied backgrounds

The general matching of shell colours to background colours seen in terrestrial gastropods implies that, as in insects, visual predation is an important factor which has a long term directional effect. Polymorphism in snails is associated with background heterogeneity, but the causal relation of polymorphism to heterogeneity is not obvious. Predation could maintain polymorphism if predators are frequency dependent in their choice of prey. However, the appropriate predator behaviour does not depend directly on background heterogeneity. An indirect contribution could be that the heterogeneity serves to lower the signal:noise ratio during the predation process. Background heterogeneity could have a direct effect if the background provided specific elements mimicked by the morphs. The remaining diversity could aid the process by lowering the signal:noise ratio. Polymorphism could be maintained if there was frequency-dependent niche selection on the part of prey. Background diversity would then be directly involved. It is necessary that there should be independent control of numbers in the different niches. In warm conditions the niche selection could come about because darker morphs, which gain more radiant heat than paler ones, will move to more cryptic sites by seeking the shade. For morph frequences to approach equilibrium values closely it is necessary for the alleles controlling the polymorphism to exhibit dominance. Differences in received energy could make pale morphs disadvantageous compared with dark ones at low temperatures but advantageous at high ones. In spatially varied temperature conditions a polymorphism could be generated without predation. Density-dependent selection is again required.     

Grazing by oligochaetes and snails on epiphytes

SUMMARY. 1. The isotope ³³P was used to assess the effect of grazitig by oligochaetes (mainly Stylaria lacttstris L.) and the snail, Lymnaea peregra (Muller), on epiphytes within an Equisetum fluviatile L. stand.
2. Two 1 m² polystyrene enclosures were set up within the emergent macrophyte zone of the lake. At the start of the experiment ³³P-solution was mixed with the water in both tanks. Algal and animal samples for ³³P- analysis were collected during the peak occurrence of epiphytes in June.
3. Phosphorus release rates from the animals through defaecation and excretion were measured in the laboratory. The grazing rate of oligochaetes was 2.2–4.1 mg P m⁻² (of bottom) d⁻¹ of which about two - thirds was released and recycled. The oligochaete density ranged from 13,400 to 20,900 m⁻². The snails (25 ind. m⁻²) grazed 1.2-1.5 mg P m⁻²d⁻¹of whieh about a quarter was released through defaecation and excretion.
4. Daily consumption by the oligochaetes and snails corresponded to 22–45% of the average phosphorus uptake by the epiphytes.     

上海地区几种常见蚊虫越冬情况的观察

1953—1954年我们曾在上海地区对几种常见蚊虫的越冬情况作了一些观察,兹将所得结果简述如下:     

Invertebrate resources on the internet

The use of invertebrates in research laboratories, classroom teaching, and public displays has greatly increased over the past 20 years, accompanied by a corresponding increase in the amount of online information and literature about invertebrates. This brief overview of Internet resources is intended to aid both novice and experienced individuals in the search for such information.     

Laboratory protocols on the internet

Summary The World Wide Web (WWW) is of major significance to the Biotechnologist. One of the fastest growing and most useful areas of the internet, the WWW contains information sites, genome and sequence databases, newsgroups and forums, search and comparison tools, and electronic journals. To many scientists, the WWW has become an indispensable research tool. This paper lists some of the sites providing a wide range of relevant protocols and techniques and describes how to access this information.     

Designer snails

The Algorithmic Beauty of Sea Shells (2nd edn) by Hans Meinhardt Springer-Verlag, 1998. DM89.00/$54.95/￡34.00 hbk (xi+236 pages) ISBN 3 540 63919 5.     

Serological studies on the taxonomy of planorbid snails

Techniques in the application of serological studies to the family Planorbidae are described. Some results obtained using hyperimmune rabbit sera are given and reasons are outlined for the final decision to use egg albumen antigens for future taxonomic work.