Planarian Research Articles

Types of responses elicited in planaria by light.

Types of responses elicited in planaria by light.

Observations on the comparative ecology of lake-dwelling triclads in southern Sweden, Finland and northern Britain

There are more lake-dwelling species of triclad in northerm Britain (10) than in southern Sweden (7) and the distribution of some differ in the two countries over approximately comparable types of lake. Dendrocoelum lacteum (Muller) occurs in a wide range of lake types in s. Sweden but is restricted to more productive lakes in n. Britain. Polycelis nigra (Muller) (absent from Sweden) has a similar, wide occurrence in Britain. Planaria torva (Muller) is more common in s. Sweden in lakes of all types but particularly in the less productive lakes. The Polycelis species P. tenuis (Ijima) and P. hepta E. H. and Y. Melander, also the Dugesia lugubris species complex show much the same distribution in both areas. Polycelis felina (Dalyell) does not occur in Sweden. The small nuber of Finnish lakes sampled confirm the data for s. Sweden. There is significant correlation between the total abundance of triclads and both the hardness and dissolved matter contents of the Swedish lake waters. Quantitatively the s. Swedish triclad populations compare most closely with those of Mid-Scotland in the n. Britain area.

The Effect of 1,2,5,6-Dibenzanthracene on the Growth and Respiration of Yeast

Several papers have recorded the stimulation by 1,2,5,6-dibenzanthracene of the growth of a variety of organisms, such as Obelia (1), Escherichia communior (2), planaria (3), and Fusarium lini (4). The hydrocarbon has also been found to depress the respiration of brain, spleen, and liver (5). In view of the fact that cancer tissue is generally characterized by rapid growth and deficient respiration, these findings are significant, and it is surprising that so few attempts have been made to correlate the two types of action on simple organisms. In an earlier note (6) we called attention to the effect of 1,2,5,6-dibenzanthracene on the growth and respiration of yeast, and subsequently Wright and Anderson (4) showed that a soluble oxidation product of the hydrocarbon not only stimulates the growth of Fusarium lini , as indicated by dry weight determinations, but also causes a more rapid utilization of glucose. Pourbaix (7) observed that another carcinogenic agent, styryl 430, depresses the oxygen consumption of yeast and decreases alcohol formation by interfering with the phosphorylation mechanism.

Unbalance in Planarian Nutrition

Unbalance in Planarian Nutrition

Notes upon Sieboldiellina planariarum (Siebold), a Ciliate Parasite of Planaria torva

Sieboldiellina planariarum is a large astomatous ciliate parasitic in the gut of the freshwater Triclad Planaria torva. The writer's attention was first called to it at Cambridge in 1923 whilst demonstrating the structure of Planarians collected from ditches in the neighbourhood.

Physiological isolation of parts and fission in planaria

Physiological isolation of parts and fission in planaria

The reactions of planarians to light

The reactions of planarians to light

The reactions of planarians to light

The reactions of planarians to light

Regeneration of grafted pieces of Planarians

Regeneration of grafted pieces of Planarians

THE EFFECT OF TEMPERATURE ON THE REGENERATION OF HYDRA

IT has been shown that temperature has a marked effect on the regeneration of Planaria torva. Lillie and Knowlton (2) have proved by experiment that the optimum temperature at which regeneration is completed is 29?.7 C.; the minimum, about 3? C. During the last month I have made a series of experiments on Hydra viridis and Hydra grisea, in order to test the effect of temperature on the regeneration of the hypostome and tentacles. A transverse cut was made through the reproductive zone of the polyp just posterior to the ring of tentacles. The body thus deprived of hypostome and tentacles was subjected to a gradual rise of temperature. The dishes in which the Hydras were placed after the operation were partially submerged in a water bath in which the temperature varied from 26? to 320 C. Readings were taken during the day at intervals of four to six hours; the variation was never greater than five degrees. Control experiments were made at room temperature, which ranged between I8? and 24? C. Observations were made at intervals of twelve to twenty-four hours, and regeneration was considered complete when the new hypostome and tentacles had attained their normal size.

The regeneration of the nervous system of planaria torva and the anatomy of the nervous system of double‐headed forms

The regeneration of the nervous system of planaria torva and the anatomy of the nervous system of double‐headed forms

Note on the Discovery of Planaria terrestris in England.

Note on the Discovery of Planaria terrestris in England.