36o 



NATURE 



TMay 19, 192 1 



use in my work I have accumulated a considerable 

 collection of wild varieties of Primula acauUs, some 

 of which have been kept merely for observation, whilst 

 others have been used for experimental work in 

 genetics, in the course of which facts having some 

 bearing on the colour problem have emerged. 



As was inevitable, I obtained the red-flowered form 

 of the primrose very early, and soon noted its 

 occurrence in restricted areas. In Northumberland 

 and Durham I know it from only two wild stations, 

 one on the coal measures of North Durham, and the 

 other in a ravine on the slopes of Kilhope Law, at 

 the head of West Allendale, in Northumberland. The 

 latter is far above the levels of gardens, and nearly 

 800 ft. above the range of the cowslip, so that the 

 possibility of hybridity is excluded. Nevertheless, all 

 the plants bear red flowers. 



With the view of testing how the red colour was 

 inherited, several plants were transferred in spring, 

 1915, from an elevation of above 1500 ft. to our garden 

 only 30 ft. above sea-level. Although these plants 

 produced red flowers in their first season, just as their 

 relatives did in their mountain home, I made no 

 crosses that year, intending to let the plants establish 

 themselves. To my amazement, however, in 1916, 

 when they flowered, their colour was exactly that of 

 the normal primrose, and as long as I kept the plants 

 — until 1918— only normally coloured flowers appeared. 

 On the other hand, plants brought from Kilhope Law 

 to the Vicarage garden at Ninebanks (elevation just 

 above 1006 ft.) showed no change whatever in flower 

 colour. 



From, the above it is clear that the altitudes at 

 which the plants grow have something to do with the 

 problem, and that the actual agency may be the 

 average temperature is indicated by the failure of some 

 rose-coloured varieties of Primula sinensis to develop 

 their proper colour unless a certain temperature is 

 attained. 



Further evidence, indicating that the same influence 

 is at work, appears in the form of two other prim- 

 roses in my possession brought from a height ot 

 1200 ft. in Upper Teesdale. These bear yellow flowers 

 much deeper in hue than usual, and, in addition, 

 clothed with a dense vestiture of white hairs. As 

 the cowslip ascends in Teesdale to the limestone of 

 Harwood Dale (at 1600 ft.) hybridity is not excluded 

 here, but against this is the fact that although I 

 have examined hundreds of primrose-cowslip hybrids 

 I have never encountered a plant iri the least like 

 these. 



The insect to which Major Latham refers as the 

 "primrose sprite" is no doubt Bomhylius major, a 

 fly often to be seen poised, with proboscis extended, 

 over primroses in April. Aiding it in the work of 

 pollination, but carrying on their operations in a more 

 or less illicit fashion, are the thrips, Taeniothrips 

 primulae, and larvae of the Geometrid moth, Larcntia 

 didymata. J. W. Heslop Harrison. 



Armstrong College, 



Newcastle-upon-Tyne, May 7. 



Earthwomis Drowned in Puddles. 



The explanation suggested by Sir E. Ray Lankester 

 (Nature, May 12, p. 329) of the occurrence of dead 

 earthworms in surface "puddles" described by Mr. 

 Friend had occurred to me, viz. that thev were 

 drowned. A3 to the survival of such worms in cool, 

 cieat, running water for some time, it is well known 



NO. 2690, VOL. 107] 



to most "bottom" fishermen that worms will sur- 

 vive for a considerable time on a hook in such Vk'ater, 

 and it is conceivable that their ultimate death is due 

 to a too free exchange between the body-fluid and 

 the surrounding water at the wounds made by the 

 hook rather than to inability to breathe. 



I walk warily in dealing with zoological matters, 

 but I may suggest that with the breathing apparatus 

 described the "moist surface" must, when under- 

 ground, frequently or usually be in contact with other 

 moist surfaces, so that the worm is, in effect, partly 

 immersed in water. The great advantage of breath- 

 ing through the agency of a moist film, as the worm 

 does when above ground and as mammals do, is that 

 the exchanges between air ai^d blood can take place 

 very rapidly owing to the steep gradient of oxygen 

 tension in the film. An animal normally living in 

 water has to expend a great deal of energy in pump- 

 ing water through its respiratory system in order to 

 get enough oxygen to support life. Fish when in 

 water very far from saturated with oxygen or 

 saturated at a relatively high temperature are unable 

 to get the water through their gills at a sufficient 

 speed; in the latter case the temperature coefficient 

 of vital activity is against them, as they live faster 

 at higher temperatures. 



The oxygen dissolved in^ water is very small in 

 amount. At 15° C. it is about 7 c.c. per litre, or one 

 part by weight in 100,000. The oxidisable matter 

 in moderately contaminated water will consume about 

 02 to 04 part of oxygen in five days at 18° F. 

 (Adeney's test). The consumption of oxygen would 

 naturally be relatively rapid in the early stages. 

 Rain-water is approximately saturated with oxygen, 

 but the considerable mass of oxidisable matters in 

 dead and rotting leaves might easily take up the 

 dissolved oxygen much more rapidly than re-absorp- 

 tion could take place in a stagnant pool of appreciable 

 depth. If so, the worms which might manage to 

 keep going for a time in well-aerated water, although 

 with difficulty, would die in water which did not 

 continually provide a surface layer fully saturated with 

 oxvgen in contact with their skin. 



I hope to be able to make some quantitative inves- 

 tigation of the matter. J. H. Coste. 



Teddington, May 13. 



The Physical Continuity of "Space." 



In the "space-aether" discussion clarity is lost by 

 a failure to distinguish between "container " and "con- 

 tent." The relativist does not assert that there is 

 no content. He is concerned with the geometry of 

 the container; if this geometry assists the meta- 

 physician or philosopher to a better understanding 

 of the content,' he is satisfied. If the container is 

 called the world-frame (a term free from the ambiguity 

 of eether), the relativist maintains that its geometry' is 

 four-dimensional and hyperbolic (semi-Euclidean) in 

 character so long as the content is free from the 

 influence of energy. This may be a condition of 

 absolute rest or it may not. When the content is 

 disturbed and energy manifested, the world-frame 

 geometry is altered, and the world-frame may then 

 be better described as the world-fabric. 



Einstein relates the intensitv of disturbance to the 

 change in the geometry of the fabric with respect to 

 that of the frame. He does not concern himself with 

 the content of the frame, but onlv with that content 

 of the fabric which manifests itself as free or bound 

 energy. He leaves it to the metaphysician to deduce 



