August 8, 1918] 



NATURE 



455 



In the section dealing with insecticides and so-called 

 repellents, the results of the great mass of experi- 

 mental work are tabulated in detail, an unavoidable 

 course owing to the wide diversit)' of method employed 

 by the various workers. In these experiments lice 

 and nits were immersed in, brought into contact with, 

 and submitted to the action of the vapour of various 

 substances and preparations. 



We heartily congratulate the author on this valu- 

 il)le and exhaustive paper, and commend its careful 

 -ludy to all those concerned with the suppression of 

 body-vermin. 



MARINE BIOLOGY AT PLYMOUTH. 



T^HE latest issue (vol. x.. No. 4, May, 1918) of the 

 ■•• Journal of the Marine Biological Association 

 contains several papers of interest to fisheries inves- 

 tigators. Mr. D. Ward Cutler writes on the question 

 of age-determination in fishes by inspection of the 

 growth increments in the scales. The latter are built 

 up of "sclerites," which are arranged in concentric, or 

 rather confocal, bands, the focus being somewhere near 

 the middle of the scale. Some of the bands of sclerites 

 (those formed during the summer months) are rela- 

 tively wide; the others that are formed during the 

 winter months are relatively narrow. Thus the scale 

 shows "annual rings of growth." 



Mr. Cutler graphs his measurements of the sclerites, 

 but gives a very bare account of the construction of 

 the figures, so that his charts are not easy to under- 

 stand. Plaice and flounders were kept in tanks arti- 

 ficially heated or cooled or of normal (seasonal) tem- 

 perature. Some of the normal tanks were well sup- 

 plied with food, and others were scantily supplied. 

 Thus it became possible to distinguish between the 

 temperature and the nutritional factors of growth. 

 The latter do not affect the formation of broad 

 (summer) and narrow (winter) bands. Abundant food 

 leads to the production of many sclerites and meagre 

 nutrition to few, but the relative width of the sclerites 

 (and therefore of the confocal bands) is independent 

 of food supply. On the other hand, the temperature 

 of the water in which the fish lives influences directlv 

 the size of the sclerites, for those formed during phases 

 of relatively high sea-temperature are large, while 

 those formed during colder periods are small. Thev 

 are formed in bands, and so the relative width of 

 the latter reflects the annual wave of temperature 

 change — even, Mr. Cutler suggests, the aperiodic 

 fluctuations of the latter. All this is in line with other 

 work on the metabolism of marine animals ; it is 

 really a case of velocity of chemical reaction, being 

 proportional to some function of the temperature at 

 which the reaction occurs. When the sea is relatively 

 warm assimilation is speeded up, respiratorv move- 

 ments in a fish are quickened, and feeding increases. 

 Decrease of temperature reduces tissue waste, and 

 events happen in the opposite direction. But assirriila- 

 tion increases absolutely during the warmer phases' 

 and so the marine fish " puts on flesh " during the 

 summer months. 



In the same journal Miss Marie Lebour gives exten- 

 sive lists of the nature and relative abundance of the 

 organisms forming the food of small, larval, and post- 

 larval fishes of various species. She confirms, in 

 general, but greatly amplifies, the observations of 

 previous workers on the same subject. Even in quite 

 small fish of some species, and with varietv of food 

 available, there is selection and quite evident pre- 

 ferences for certain food organisms. The paper is 

 Illustrated with some very admirable drawings of the 

 heads of post-larval Pleuronectid fishes. J. J. 



NO. 2545, VOL. lOl] 



SCIENCE IN HORTICULTURE. 

 npHE third annual report of the Nursery and 

 Market Gardens Industries Development Society, 

 Turner's Hill, Chesbunt, shows that continuous pro- 

 gress is being made in the application of science to 

 horticultural practice. The fertiliser experiments are 

 of considerable interest, and bring out the marked 

 effectiveness of nitrogen compounds, especially of 

 stable manure, in the growth of cucumbers, and 

 their relative ineffectiveness in the growth of toma- 

 toes. It is not definitely settled whether this result 

 arises from some fundamental difference in the method 

 of nutrition of the two plants, or siniplv from the 

 relative drafts they make on the soil. The ineffec- 

 tiveness of phosphates, both on cucumbers and toma- 

 toes, is remarkable, and merits closer attention. An 

 important technical matter is the dexnonstrat'ion that 

 a relatively inexpensive mixture of artificial fertilisers 

 gave larger returns than a mixture made bv some of 

 the best growers based on the best practice of the 

 district. Fertiliser trials need considerable time for 

 their execution, and it must be some time still before 

 the experiments have yielded all the information they 

 are capable of giving. They seem to support the old 

 idea of an antagonism between fruiting and vegeta- 

 tive growth, for the methods which would normally 

 produce the largest plants do not necessarily produce 

 the largest amount of fruit. 



Some interesting observations are recorded on the 

 physiological conditions in cucumber-houses. There 

 was found to be an appreciable correlation between 

 the area of the seed-leaves and of the first rough leaf, 

 and also a small correlation between the size of the 

 seed-leaves and the dry weight after thirty days. 

 Seedlings with the longest stems gave the largest 

 crops. All these points are of great importance; it 

 is remarkable that the later history of the plant should 

 be so intimately bound up with its early properties. 

 The grower has room in his houses onlv for a very 

 limited number of plants, and he cannot afford to 

 keep unprofitable seedlings. 



Further experimental work was also undertaken on 

 methods for the partial sterilisation of soil, and a 

 serious combined effort is being made to solve the 

 problems arising when these are applied in practice. 



THE PALEOBOTANY OF NEW ZEALAND.^ 

 np HE late Dr. Arber's memoir on the earlier Mesozoic 



*■ floras of New Zealand is a particularly welcome 

 addition to our knowledge of a much-neglected sub- 

 ject. In 1913 Dr. Arber published two papers on fossil 

 plants frorn New Zealand, but the present paper covers 

 a much wider field and deals very fully with a con- 

 siderable number of species from Triassic-Rhaetic, 

 Jurassic, and Cretaceous strata. The specimens are 

 the property of the Geological Survey of New Zealand, 

 the British Museum, and the Sedgwick Museum, 

 Cambridge. 



The author shows that no Palaeozoic plants have 

 so far been discovered, and no undoubted examples of 

 Glossopteris are included in the material examined. 

 The genus which most nearly resembles Glossopteris 

 is Linguifolium, instituted by Arber in 1913, but the 

 author does not believe that the two are closely allied. 

 The arguments in support of his view are, however, 

 not conclusive. It is assumed that New Zealand did 

 not form part of Gondvvanaland, this term being used 

 by Arber for a Palaeozoic continent only, a more 

 restricted usage than that adopted by Suess and some 

 other authors. 



1 " The Earlier Mesozoic Floras of New Zealand." By Dr. E. A. Newell 

 Arber. New Zealand Geological Survey : Palxontological Bulletin, No. 6, 



