September i, 1921] 



NATURE 



of lower centres to appear. These unfettered mani- 

 festations are not fortuitous patholc^ical states, but 

 represent that part of a complex reaction which still 

 remains active." .It is impossible within the scope 

 of a note such as this to give any adequate idea of a 

 lecture that is itself the highly condensed summary 

 of thirty years' research into problems of great in- 

 herent complexity which have become obscured by 

 erroneous methods of interpretation. Dr. Head's 

 work is a brilliant example of the successful applica- 

 tion of the true scientific method in clinical medicine, 

 and is complementary to Prof. Sherrington's inves- 

 tigation of the same sort of problems by the experi- 

 mental method. Much as their researches are mis- 

 understood and however inadequate the appreciation 

 of their worth may be at the present time, there can 

 be no doubt that in the future Head's and Sherrington's 

 work will be known as the outstanding achievement 

 of British science in neurology and the borderland 

 between neurology and psychology. Dr. Head's con- 

 tribution to this great advance in knowledge is well 

 -et forth in his Croonian lecture. 



Dr. J. Ritchie contributes to the Scottish Naturalist 

 (May-June, 192 1) an interesting analysis of the status 

 of the walrus as a member of the British fauna. He 

 supposes that when the polar ice sheet extended much 

 further south, and during its retreat in the late Ice 

 age, the walrus was a regular inhabitant of British 

 seas, and the evidence, though scant\-, goes to show- 

 that even down to the sixteenth centur\- it was regu- 

 larlv hunted by the islanders of Scotland for com- 

 mercial purposes. In an analysis of the twentj-four 

 records since 1800 Dr. Ritchie concludes that a change 

 in its status has occurred, and that it is now only 

 a straggler which chance conditions bring occasionally 

 to our shores. Summer is predominantly the season 

 for its visits, and its appearance in British waters is 

 associated with the breaking-up of the winter ice of 

 the Arctic and its gradual drift to sea under the 

 influence of ocean currents and winds. The majority- 

 appear to have travelled from a westerly source towards 

 Iceland, brought there by unusual developments of 

 the Greenland-Iceland-Faroe oceanic circulation. A 

 marked decrease in the numbers obsersed in British 

 waters occurred after 1870, which Dr. Ritchie attri- 

 butes to the activities of seal-hunters about that period 

 in clearing the more southerly breeding-grounds off 

 Greenland of their stocks. 



In an interesting article on "Snakes that Inflate " 

 in Natural History (vol. 21, No. 2), Mr. G. K. Noble 

 discusses the significance of an aggressive warning 

 attitude assumed by certain snakes when disturbed. 

 In Spilotes puUatus mexicanus, a harmless snake, 

 he found that the animal, when uneasy or in a highly 

 ner%ous state, inflated- its neck and vibrated its tail, 

 recalling the warning attitudes of cobras on one hand 

 and of rattlesnakes on the other. The mechanism 

 by which the snake is able to inflate itself is simple. 

 The dorsal membrane of the trachea is an enormously 

 expanded sheet capable of great distension, and the 

 snake simply fills its lungs with air, closes the glottis, 

 and. by means of its powerful body muscles, forces 

 NO. 2705, VOL. 108] 



the air into the trachea, which then becomes dis- 

 tended. Mr. Noble finds this habit developed in many 

 species of snakes, generally harmless, belonging to 

 quite separate families, and the mechanism is in all 

 cases the same. He regards the character as having 

 arisen independently in a number of unrelated groups 

 of snakes, and as an impressive example of parallelism 

 in adaptation. Similar evidence is noted about the 

 habit of vibrating the tail when disturbed. While 

 admitting that both phenomena may be called warn- 

 ing attitudes, he suggests that both actions may be 

 simply manifestations of an. uncomfortable ner\-ous 

 state produced by the presence of some disturbing 

 factor in the environment. 



A RAIN map of Australia for the year 1920 has been 

 issued by Mr. H. A. Hunt, Commonwealth Meteoro- 

 logist. The distribution of rainfall in different parts 

 of Australia is shown graphically for the year, and on 

 the reverse side there is a rainfall map for each of the 

 twelve months. For comparison a small map of Aus- 

 tralia is given for each year from 1908 to 1920, which 

 shows the percentage of the area with the rainfall 

 above the average. In 1918 only 23 per cent., and 

 in 1919 only 13 per cent., of the area received more 

 than average rainfall ; in 1920, however, on 54 per 

 cent, of the area rainfall was above the average. 

 The single sheet is admirably arranged, and the large 

 amount of data in no way overcrowded. It affords 

 a specimen for any rainfall organisation, and a 

 similar sheet would be greatly appreciated by those 

 interested in rainfall distribution in an}* country. A 

 summar}- table and notes on the 1920 map are given. 

 It is stated that the year will be memorable cm 

 account of the complete change from unpromising 

 weather conditions during the early months to wide- 

 spread rains in the latter half. The long drought 

 which had prevailed over central and eastern Aus- 

 tralia since the early part of 19 18 was completely 

 broken up. The splendid rains during the greater 

 part of the agricultural season, April to October, are 

 said to have resulted in one of the best harvests on 

 record all through the wheat-belt. Brief summaries 

 of the rainfall distribution in 1920 are given for each 

 State. At many stations in South Australia 1920 

 was the wettest year on record. 



Mr. E. T. Ouayle (Proc. R. Soc. Victoria, new 

 sen, vol. 33, pp. 115-32, 1921) has issued an 

 optimistic estimate of the beneficial effects on the 

 climate and rainfall of Victoria and of the southern 

 districts of New South Wales that may be expected 

 from irrigation. He illustrates the fact that the lee- 

 ward shores of wide arms of the sea have usually 

 a higher rainfall than the windward shores by refer- 

 ence to the records from Spencer Gulf and Port 

 Phillip. He considers that the extension of irrigation 

 in the Murray valley may have the same effect as 

 if the irrigated region were covered by an arm of 

 the sea. He claims that higher evaporation will 

 increase not only the local rainfall, but also 

 that on the mountains in which the Murray 

 River and its tributaries take their rise, so 

 that the rivers will be magnified, and the benefits 



