摘要:

Summary..In view of the growing importance of fish for native consumption, the resources of the African lakes are sure to be exploited in the near future, but it is essential to have a sound understanding of the fish and other fauna and flora in each lake before exploitation is started. This paper places on record the available data for Lake Rudolf and Lake Baringo, on which no previous ecological work had been attempted.Lake Rudolf is characterized by a high temperature and very alkaline water, and contains a variety of environments inhabited by different fish‐associations. The fauna has pronounced nilotic affinities, except that there is only one member of the family Mormyridae. Several species, however, have come to differ from their nilotic ancestors, and the comparison of the fauna with that of other waters can be used as evidence for past changes in the drainage systems of East Africa.The fish fauna of Lake Rudolf is roughly divisible into three main associations of species–one in the inshore waters, one in the open water, and one near the bottom. Prom data supplied by large numbers of stomach examinations, the food‐chains for each of these habitats can be reconstructed.Lake Baringo is less warm, the water has a relatively low alkalinity, and is uniformly shallow and muddy. The fish fauna consists of few species, and shows affinities with that of the East African rivers which flow to the Indian Ocean.Owing to the shallowness of Lake Baringo, there is no differentiation into species‐associations, and the food‐chains are complicated by the presence of food from the bottom in all the species of fish.The bulk of this paper contains analyses of field‐observations on the size, feeding and breeding habits of each of the species found i

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00472.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00473.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00474.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00475.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

Summary.Observations from the jetty of the Biological Station, Bermuda, of the appearance ofAnchistioides antiguensis(Schmitt) at the surface over a short period in 1934 and eight months in 1935 are recorded, and show definite periodicity sometimes of sufficient intensity to merit the term swarming.The periodicity coincides with the two weeks of the lunar cycle when the moon wanes from the last quarter to the first quarter of the new cycle. It appears to consist of two maximum appearances separated by an interval of some days.Direct lunar influence, sex and the reproductive period, the surface‐temperature, wind and weather, and the state of the tide are shown to have no connexion with swarming.An explanation is suggested based on the feeding habits and depending on the periodic activity of the worms that form the food. The double maximum of the swarming period is shown to represent two stages of growt

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00476.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMABY1The rearing ofBalanusnauplii in the laboratory and the stage at which hatching occurs are discussed.2The external morphology of the second stage nauplius ofBalanus per‐foratusis described. The setae on the limbs I divide into two types– swimming setae and feeding setae.3The limbs beat in a metachronal rhythm. During the back‐stroke particles are swept backwards and inwards, converging from each side just behind the body. From here they are sucked forward along the ventral surface during the fore‐stroke of the mandibles and antennae.4They are retained in the region behind the labrum by the feeding setae and their setules, by spinules on the ventral surface of the body, and by setules on the tip of the labrum.5As the limbs beat back the feeding setae push the particles towards the mouth. A groove under the labrum leads to the mouth itself, into which the particles are pushed by prongs on the antennal jaw processes.6Feeding is rapid and not selective. But particles over 6/x indiametercannot be swallowed, though diatoms 25fi longare freely taken. It appears that single cells may be torn from filamentous algae and then swallowed. But there is never any true mastication, and larger bodies do not form part of the food.7The first stage nauplius does not feed. The mouth is apparently open, but the feeding structures are very rudimentary, and particles can thus reach the mouth only by a

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00477.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

Summary.1In connexion with an investigation of the reproduction of organisms in a climate which varies little during the year, meteorological observations were made from September 1933 to August 1934 at Hog Harbour, Espiritu Santo, New Hebrides (15o15′ S. latitude). Special attention was paid to the measurement of the climate in which the animals actually live, namely in the rain‐forest.2In general, the climate at Hog Harbour is hot and wet from June to October, and slightly hotter and considerably wetter from November till May. There is no dry season, the least wet month having, on the average, about twice as much rain as the wettest month in England. The year under investigation conformed to the average except that April and May were less wet than usual.3The mean temperature only varied by 2o‐l C. (3o‐8 F.) between the hottest and coldest months. In England during the same period the seasonal change was about eight times as great.4The distribution of rainfall is exceptionally unseasonal for a tropical region, since the wettest month receives on the average only 2–5 times as much rain as the least wet. An analysis of meteorological data from the whole of the tropics shows that such a low figure as this is very rare.5The cooling power of the atmosphere, as measured by the kata‐thermo‐meter, was greater in July and August than in the other months, but the difference was small.6There is no obvious seasonal distribution of daily hours of sunshine, but there appears to be much less ultra‐violet light in certain months (e.g. June) than in others.7The saturation deficiency of the atmosphere was almost uniform throughout the year, except that it was higher during April and May. The amount of evaporation varied considerably from month to month, without disclosing any distinct seasonal tendency.8Barometric pressure varied only very slightly during the year, but its variations were very regular and indeed constitute the most regular seasonal change observable

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00478.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

Summary..Studies of the biology of two species ofEmpriaLep.,E. abdominalisF. andE. tridensKon., reveal thatE. abdominalisis a multivoltine species with thelytokous parthenogenesis andE. tridensis a univoltine species with arrhenotokous parthenogenesis.E. abdominalisis associated withAnagallisandLysimachia,and lays large conspicuous eggs in the under sides of the leaves.E. tridensfeeds onRubusspp., and inserts small inconspicuous eggs into stems, leaves, and bud scales of the host plant.Larvae of both species are closely and evenly annulated. A typical abdominal segment has six annulets; inE. abdominalisthe second and fourth annulets are setiferous, while inE. tridensthe first, second, and fourth annulets are setiferous. Prolegs occur on segments 5–11 and 13 in both species and pseudocerci are absent. Larvae ofE. abdominalishave the back and sides covered with a fine flaky or powdery substance which is absent in larvae ofE. tridens.Females ofE. abdominalishave six larval stages, in the last of which no feeding takes place. Males ofE. tridenshave five larval stages, in all of which feeding occurs.InE. tridenshibernation and pupation take place within bark, dead wood, and pithy stems, while inE. abdominalispupation takes place in the soil. Neither species constructs a cocoon.The differences in biology and habits seem to justify the subdivision of the genus by Enslin into subgenera–MonostegiaCosta, which includesE. abdominalis,andTriempriaEnslin, which includesE. trid

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00479.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00480.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

Summary.1In the relatively unvarying climate of the northern New Hebrides (about 15oS. in the Pacific Ocean), most of the plants studied present seasonal reproductive phenomena.2There is a tendency for plants to flower and fruit from September to January or February and again in May and June.3The start of the longer flowering season coincides with the rise of temperature after the end of the cooler period of the year. The rainiest months of the year occur during this long flowering season.4Two of the plants studied–namely, the herbGeophila herbaceaand the shrubPiper meihysticum–reproduce throughout the year, and possibly the same applies to the treeFicus copiosa.5The natives rely upon the flowering and fruiting of certain wild trees to determine the time for planting certain crops (yams and sweet potatoes).6Of the cultivated perennial plants, the bread‐fruit and orange are seasonal, while the banana and papaw produce fruit throughout the year.7Seasonal phenomena in reproduction and leaf‐fall depend partly on an internal rhythm and partly on the environment, and in the interplay of these two controlling factors the one dominates in some species, the other in

ISSN:0368-2935    

DOI:10.1111/j.1096-3642.1936.tb00481.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY