456 



NATURE 



[April 8, 1922 



Research Items. 



The Organism and Environment. — In an article 

 on "The Organism and its Environment" [Scientific 

 Monthly, March 1922), Dr. F. B. Sumner emphasises 

 the difficulty of drawing any sharp line between these 

 two categories. Citing as examples the nest of a 

 bird, the tube of a caddis-worm, the shell of a mollusc 

 or a tortoise, the varying fluids and gases which 

 circulate in animals from sponges to fishes or seals, 

 and the many metabolic changes of substances enter- 

 ing or leaving the body, he shows that the distinction 

 between organism and environment must often be 

 difficult or arbitrary. Some of his remarks have a 

 direct bearing on the discussion of biological termin- 

 ology which has taken place recently in this journal. 

 Thus he says, " Every character has a hereditary 

 basis " and is likewise due to " interaction . . . with the 

 . . . environment." He goes on to say, " The familiar 

 question. Which is the more important, heredity or 

 environment ? is not capable of answer when stated 

 in that form " ; he points out that the question 

 should be framed on these lines : Are the differences 

 between related organisms in any particular case, 

 due to differences in heredity or to differences in 

 environment ? When stated in this way it is seen 

 that some characters or differences are primarily due 

 to heredity and some to environment, and the quibble 

 about all characters being equally acquired and 

 equally inherited ceases to be of scientific value. 



Studies on Arthropoda. — Dr. H. J. Hansen has 

 issued, " at the expense of the Rask-Orsted Fund," 

 under the title " Studies on Arthropoda, I." (Copen- 

 hagen, 1921), three papers — one, illustrated with four 

 plates, on a collection of Pedipalpi, etc., from West 

 Africa, another on the post-embryonic occurrence of 

 the median " dorsal organ " in Crustacea, mala- 

 costraca, and a third on stridulation in decapod 

 Crustacea. In this last paper Dr. Hansen has brought 

 together the records of the species of decapods in 

 which stridulating organs are present, and gives an 

 account of two further examples which he has dis- 

 covered in a species of Ovalipes (one of the Portunidae) 

 and in Acanthocarpus (family Calappidae). A stridu- 

 lating organ consists usually of a regular row of small 

 tubercles or a file-like series of ridges, e.g. on the 

 carapace, which can be rubbed by a ridge, or a regular 

 row of tubercles or ridges, or a sharp margin situated 

 on some movable part of a neighbouring appendage. 

 The sound produced by living crabs by means of the 

 stridulating organ has been heard in the case of about 

 half a dozen species. Dr. Hansen points out that a 

 stridulating organ is developed in all species of 

 Ocypoda except one, and in the Indo-Australian 

 Ocypoda ceratophthalma one of the two series of ridges 

 is composed of ridges of two sizes, coarse and very 

 fine, so that the tone produced is deep or high, 

 according as the coarse or fine ridges are rubbed. In 

 discussing the use of the stridulating organ Dr. 

 Hansen quotes Col. Alcock's view that this organ 

 serves the crab to give warning to trespassers of its 

 own species about to enter its burrow, but he suggests 

 that some naturalist who has at his disposal living 

 examples of Ocypoda should carry out investigations 

 with the view of elucidating further the use of these 

 organs. 



Hygrometry. — The report of the discussion on 

 hygrometry which was held by the Physical Society 

 of London in November last has been issued with the 

 Proceedings of the Society for February 15. It 

 extends to 95 pages and is the most comprehensive 

 publication on the subject which has appeared for 



NO. 2736, VOL. 109] 



many years. For some time one of the principal 

 problems of hygrometry has been to develop a method 

 which would determine, with an accuracy of i per 

 cent., the fraction of saturation of air at tempera- 

 tures below the freezing - point of water. The 

 chemical method of absorbing the moisture is quite 

 satisfactory at ordinary temperatures, but at tempera- 

 tures below the freezing-point, the weight of moisture 

 present is small and the method becomes difficult 

 owing to the deposition of dew on the weighing tubes 

 and other apparatus used. The dew-point method 

 in its various forms is applicable at all temperatures 

 and has been employed at the National Physical 

 Laboratory as the standard of reference. The wet 

 and dry bulb instrument fails at temperatures below 

 the freezing-point, while the hair hygrometer con- 

 tinues to act although its indications are not always 

 trustworthy. There appear to be some grounds for 

 taking the decrease in length of the hair from its length 

 when saturated as proportional to the logarithm of 

 the relative humidity down to a relative humidity of 

 10 per cent. 



Liquid Inclusions in Glass. — Some interesting 

 experiments on the production of liquid inclusions 

 in glass, made by Mr. Charles E. Benham, are 

 described in the Geological Magazine for March. 

 Although liquid inclusions in crystals of sodium 

 chloride, alum, and other salts resemble in many 

 respects those in quartz and exhibit Brownian 

 movement of the more minute enclosed bubbles, 

 there is reason to believe that their origin is not 

 the same. Artificial inclusions approximating more 

 closely to the cavities in minerals were prepared by 

 boiling resin in water tinted with gamboge. Some 

 of the cavities produced contained sm^all quickly 

 moving bubbles, and in others the gamboge particles 

 were in rapid motion. In order to form similar 

 artificial inclusions in glass approximating more 

 nearly to those found naturally in quartz, a small glass 

 tube about 3 inches long and a quarter inch external 

 diameter was partially filled with water and sealed at 

 both ends. It was enclosed within an unbaked brick 

 and submitted to the usual process of firing in a brick 

 kiln at a temperature of about 1200° C. After this 

 treatment the glass was found to contain microscopic 

 liquid inclusions with vapour bubbles comparable 

 with those found in quartz. The experiment was 

 repeated with similar results. 



The Atomic Weight of Chlorine. — From the 

 researches of Dr. F. W. Aston it is known that 

 ordinary chlorine, atomic weight 35-46, is a mixture 

 of two isotopes of atomic weights 35 and 37. The 

 constancy of this ratio has been proved by the con- 

 cordance between the determinations of the atomic 

 weight made in different laboratories. This chlorine, 

 without exception, came from minerals deposited by 

 sea water. There is a possibility that the ratio 

 might not be the same in chlorine arising from primary 

 minerals not deposited from sea water, and this 

 question has been taken up by Mile. Ellen Gleditsch 

 and B. Samdahl {Comptes rendus, March 13). They 

 prepared salt from an apatite (calcium chloro- 

 fluophosphate) found in primary rocks, and after 

 careful purification from fluorine, bromine, and 

 iodine, found the atomic weight of the chlorine to be 

 35'49. 35'45' 35'4^> the same as that of ordinary 

 chlorine. Hence at the time of the formation of 

 the minerals of the primary magma, the two chlorine 

 isotopes were in the same ratio as at the present 

 time. 



