Lunar Periodicity Research Articles

Light as a Factor in Reproductive Periodicity

IN a letter to NATURE1 I observed that the culture of diatoms in polarised light would be an interesting piece of research. Later, I placed a culture in a small tube in the path of light from a Nicol prism, and a similar tube using the same culture medium, in ordinary daylight: at night, light from the sky was admitted as in the day. The rate and prolificacy of reproduction were approximately the same. It appears from this that it is the length of the period of exposure, and the intensity of the light which are the chief factors; the polarisation of the light is of little importance. In this case it looks as though reproduction at night has no connexion with lunar periodicity.

Hydrolysis in Green Plants by Moonlight

IN view of the recent interesting discussion on ‘Lunar Periodicity in Organisms’, which has appeared in these columns,1 some very simple experiments, carried out in South Africa in the grounds of Huguenot University College, would appear to throw some light on the subject.

Lunar Periodicity in Reproduction

A NUMBER of living organisms, particularly marine animals, exhibit a lunar periodicity in reproduction.1 Tides do not seem to be a causal factor in this phenomenon, and it has been difficult to understand how moonlight could be responsible, since the intensity of the light of the full moon is only about 1/500,000th that of sunlight.

A theory regarding the role of insect saliva in filarial periodicity

The hypothesis is presented that there is a positive specific chemiotaxis acting on microfilaria; to cause them to migrate toward the saliva of the insect host, and that this same substance may furnish the stimulus for cyclical parturition of the adult filaria. The bite of a hyperfilariated Culex fatigans may be a factor in initiating certain attacks of lymphangitis in Porto Rico showing a lunar periodicity.

NATURAL HISTORY OF SHIPWORM,TEREDO NAVALIS, AT WOODS HOLE, MASSACHUSETTS

Teredo navalis occurs in abundance at Woods Hole and vicinity and has been known there for many years.The breeding season extends from about May 10 to October 10. Spawning begins in the spring when the water reaches a temperature between 11° and 12° C. Spawning by each female occurs several times during the season. No lunar periodicity in spawning occurs and there are no broods caused by synchronous spawning.The eggs are retained in the gills of the mother during cleavage and early larval development.The time required for the fertilized egg to complete larval development to metamorphosis is approximately five weeks at Woods Hole. About half of this time is passed in the brood pouch and half as a free swimming veliger.When eggs and early embryos are removed from the gills they do not develop normally.The trochophore of Teredo is non-motile, having either a feebly developed protroch or none.Teredo navalis reaches sexual maturity in six weeks or two months after metamorphosis when it measures four or five centimeters in length. It reaches adult size in on year, and dies during the second year. The largest specimen collected in four years measured forty centimeters in length and one centimeter in greatest diameter.The rate of growth during the summer months and also during the winter was determined and tabulated. Certain habits of shipworms were also observed and recorded.

On Lunar Periodicity in Reproduction of Pecten opercularis near Plymouth in 1927–28

SUMMARYIt has been shown that there is a lunar periodicity in reproduction of P. opercularis near Plymouth in 1927-28. The ripening of sexual products corresponds with the full phase of the moon.The condition and shape of the gonad changes with the development of the tissues.The colour, too, of the hermaphrodite organ changes with development.Black pigmentation has been observed on the gonad in thin-shelled P. opercularis, a phenomenon apparently due to actinic rays penetrating the thin shell.The breeding season is from January to June inclusive.The gut contents seem to show no appreciable difference either in quantity or in the natureof the food during a lunar month.The moonlight has apparently no effect on the lunar periodicity in reproduction.It is suggested that in the animal there is a physiological rhythm that causes the development of the gonad to coincide with the full moon of each lunar month

AN ANALYSIS OF THE SPAWNING HABITS AND SPAWNING STIMULI OF CUMINGIA TELLINOIDES

1. The spawning season of Cumingia extends from the middle of June until the middle or end of September. The most active spawning usually includes the last week in June and ends about August 20. Each female spawns more than once and the production of gametes is practically continuous.2. The spawning is heaviest from full moon to new moon and least at first quarter thus showing a lunar periodicity.3. Cumingia is greatly affected by shock and rough treatment so that sexually mature individuals spawn promptly when brought to the laboratory, after being placed in a bowl of quiet sea water.4. There are apparently no chemical stimuli by which the sexes stimulate each other to sexual activity as is the case in Nereis limbata and the oyster. They spawn as readily when isolated as when in close proximity.5. It is shown that temperature is not the only factor which determines the duration of the spawning season and periods of spawning.

On Lunar Periodicity in Spawning of normally grown Falmouth Oysters (O. edulis) in 1925, with a comparison of the spawning capacity of normally grown and dumpy Oysters.

During 1925 dumpy oysters spawned in a high proportion on the Fal beds, and although not such heavy breeders as normal oysters, they are undoubtedly valuable in forming a stable spawning stock for replenishing the beds in the future. Nearly every normal and dumpy oyster above a size of 2 to 2\ inches produced at least one batch of spawn in 1925. Since dumps increase in proportion on the beds as over-fishing occurs, they form a natural breeding reserve for repopiilating the beds in favourable years, as there is no adequate reason to suppose that the larvae of dumps are unhealthy. Weekly samples of oysters examined closely during the summer of 1925 for the percentage of spawning females and ripe but unspawned females show

Lunar Periodicity in Obelia

IN Proc. Roy. Soc., vol. 95, 1923, Mr. H. M. Fox directed attention to a number of cases of “Lunar Periodicity in Reproduction” in marine organisms. To these may be added the hydroid Obelia geniculata. At first sight the periodicity is masked by the irregular breeding of colonies which are wave-worn or much eaten down by nudibranchs, but if attention is confined to healthy and perfect colonies, the lunar periodicity seems quite definite. During 1924 several colonies on the piers were located and watched; the best result was from a colony on Laminaria on Millport old pier, which was giving off medusae during the ten-day periods beginning with the third week of the moon in July, August and September, and not at other times. Other colonies gave definite results in two consecutive months, but were then attacked by nudibranchs or lost.

Seasonal Changes in Shell-fish

MR. H. MUNRO FOX, in a paper published in the Proceedings of the Royal Society (B, No. 671) in January last, entitled “Lunar Periodicity in Reproduction,” refers to vol. ii. of the Philosophical Transactions, published March 1667, by Henry Oldenburg, Sec. R.S., wherein, at p. 419, may be found the following question, forming one of a series comprised under the heading, “Inquiries for Suratte, and other parts of the East-Indies “Whether those shellfishes, that are in these parts plump and in season at the Full Moon, and lean and out of season at the New, are found to ha\re contrary Constitutions in the East-Indies.”

Societies and Academies

Societies and Academies

On lunar and solar periodicities of earthquakes

In a paper recently communicated to the Royal Society “On Lunar Periodicity in Earthquake Frequency,” Mr. C. G. Knott gave some results, from which he argued that a real connexion between tidal effects and earthquakes probably existed. These results are based on a method which has frequently been employed. The records of earthquakes are grouped together and expressed by means of a Fourier series, and conclusions are based on the greater or smaller values of the coefficients of this series.

On lunar periodicities in earthquake frequency

1. Introduction .—The paper is a discussion of Professor Milne’s Catalogues of 8331 earthquakes, recorded as having occurred in Japan, during the eight years 1885 to 1892 inclusive. These catalogues, forming vol. 4 of the ‘Seismological Journal of Japan,’ are unquestionably the most complete ever constructed for an earthquake-disturbed country. The discussion is really a working out of certain lines suggested in a paper on “Earthquake Frequency,” communicated by me in May, 1885, to the Seismological Society of Japan, and published in vol. 9 of the ‘Transactions’ of that Society.