96 



NATURE 



[October 2, 19 19 



critical frost dates is their extreme irregularity. 

 Thus at Peoria, 111., with a fifty-nine years' 

 record, the latest frost in spring covers a period 

 of nearly fifty days, and the earliest in autumn 

 a period of forty days. The maps are based upon 

 the average dates. 



The mountainous character of the country in 

 the western portion of the United States, and the 

 fact that the stations are mostly situated on the 

 lower slopes of the mountains, make mapping 

 very difficult, and it is pointed out that only a 

 general idea of the conditions can be given. For 

 practical purposes this position of the stations 

 should not matter, as they would naturally be in 

 those parts where cultivation was most prevalent. 



It appears from the maps that there is no part 

 of the United States except Key West where a 

 frost may not occur, and the line showing a frost 

 in half the years — that is, the line showing the 

 position where a frost is just as likely to occur 

 once in the winter as not to occur- — excludes only 

 a small part of Florida and reaches down to lati- 

 ture 26° N. The line for the last frost before 

 March i cuts off the peninsula of Florida and 

 fringes the southern coast as far as New Orleans. 

 In the north frosts are common until the middle 

 of May or even June i, and in the higher parts of 

 the west, which are only used for grazing, they 

 occur after June i. 



The earliest frost in autumn does not occur until 

 after December i in Florida and in parts of the 

 south-west. On the north-western frontier frost 

 may be expected about the middle of September. 

 About one-quarter to one-third of the whole 

 country has a period of 210 consecutive days free 

 from frost, but in the mountainous regions of the 

 west there is a good deal of country in which the 

 period is barely half as long. 



Some smaller maps give information as to the 

 frequency of frosts in the different districts one, 

 two, or more weeks before or after the average 

 dates. The whole paper is most interesting, and 

 should be very useful to agriculturists in the 

 United States. , W. H. D. 



^OTES. 



There was a certain inevitableness in the nomina- 

 tion of Mr. .Arthur James Balfour for the Chancellor- 

 ship of Cambridge University. The fact that Mr. 

 Balfour has consented to be so nominated in suc- 

 cession to his late brother-in-law has everywhere 

 been received with enthusiasm. In the history 

 of Cambridge, statesmen, administrators, literary 

 men, and philosophers have succeeded one after 

 another in the roll of Chancellors, but in Mr. Balfour, 

 the most celebrated of living graduates of Cambridge 

 University, all are combined in one man. Mr. 

 Balfour is one of the two honorary fellows of Trinity 

 College, the other being the Right Hon. G. O. 

 Trevelyan. Mr. Balfour was educated at Eton, and 

 entered Trinity College in the late 'sixties. He took 

 his degree in the Moral Sciences Tripos of 1S96, in 

 the same year as Dr. Percy Gardner, now the pro- 

 fessor of archaeology at Oxford. The Balfour family 

 has been most intirnately associated with Cambridge ; 

 his vounger brother Francis, who unhappily perished 

 in the .Alps in 1882, was a man of the highest 



NO. 2605, VOL. 104] 



scientific distinction, one who was leading zoologists 

 along new lines of thought; another brother, Gerald, 

 was a fellow of Trinity ; one of his sisters married 

 Prof. Henry Sidgwick, and was for many vears 

 Principal of Newnham College ; and another sister 

 married Lord Rayleigh, whose recent death has 

 deprived the University of a generous Chancellor and 

 a great picmeer in modern physics. A reference to 

 "Who's Who" will show not only the list of 

 honorary degrees, too long to be quoted here, which 

 have been conferred upon Mr. Balfour, but also that 

 he has constantly taken the lead on various boards 

 and committees connected with education. He has 

 been Lord Rector of .St. Andrews University, Lord 

 Rector of Glasgow University, and he is Chancellor 

 of Edinburgh University. The announcement that 

 so distinguished a man and scholar has consented to 

 be nominated for the post of Chancellor has met 

 with widespread sympathy and hope amongst the 

 members of the Senate. 



Entomologists, it appears, have not jet solved the 

 problem of what becomes of the house-fly in winter- 

 time. The popular idea that when the cold season 

 comes the house-flies, or such of them as do not die 

 off, retire to some quiet nook or cranny in the house 

 and, like dormice, sleep undisturbed through the 

 winter is still entertained in some scientific and other 

 respectable quarters, although no trustworthy evidence 

 has been found to support it. There are flies and flies ; 

 and, as Dr. L. O. Howard was, we believe, the first 

 to suggest, no evidence relating to the hibernation of 

 the house-fly can be trusted until it has first been sub- 

 mitted to expert examination. Since that suggestion 

 was made, a large amount of evidence has been sub- 

 mitted to experts, and now they are almost 

 unanimously agreed that the hibernating hou§e-fly is 

 a wholly mythical creature. But the house-fly must 

 get through the winter somehow, and if not in its 

 perfect state as a fly, then in some other stage or 

 stages of its life, or else we should not be troubled 

 with the pestilent brood year after year in succession. 

 Before the entomologist can tell us exactly how, it 

 looks as if he will need the help of the sanitary 

 officer, the stable-boy, the farm labourer, or even of 

 the Boy Scout, rather than that of the ordinary house- 

 holder.' The search for larv* and pupaj of the fly 

 is not an easv one, and often involves a great amount 

 of phvsical labour. In summer-time the pupae are 

 frequently to be found living at a depth of 2 ft. under 

 the surface of the soil within half a yard of a manure 

 heap. Dr. Gordon Hewitt has searched for them in 

 such places, and in every other likely place, in winter- 

 time, and has never succeeded in finding any alive. 

 But because he, and possibly a few others, have made 

 it and failed, it can scarcely be said that a search of 

 that kind has been exhausted, and that we must fall 

 back upon the hibernating adult fly as the only 

 alternative. There may be no definite hibernating 

 stage in the life of the fly. The insect may con- 

 tinue to breed in the winter, not exactly as it does in 

 the summer or autumn, but at a greatly retarded 

 rate, each stage being more or less prolonged. This 

 probably does not happen to any extent under natural 

 conditions in this country, but the number of places 

 in which it can happen, and probably does happen, 

 under special conditions may be quite sufficient to 

 account for the perpetuation of the fly. 



The officers and other members of council of the 

 Rontgen Society for the session 1919-20 are as 

 follows -.—Vestieni : Dr. Sidney Russ. Hon. Secre- 

 taries: Dr. Robert Knox and Dr. R. W. A. Sal- 

 mond. Hon. Treasurer: Mr. Geoffrey Pearce. Hon. 



