Popular Science Monthly/Volume 64/November 1903/Shorter Articles and Discussion
THE AURORA BOREALIS OF AUGUST 21.
To the Editor: I have been much interested in the account given by Dr. A. F. A. King of the unusual aurora observed by him on the twenty-first of August at York Harbor, Maine (Popular Science Monthly, Vol. LXIII., pp. 563-4), because I also observed it the same evening from a point near Baddeck, Cape Breton Island, Nova Scotia.
My attention was called to the display about 8:45 p. m., Halifax time (this would be about 7:45 p. m. by eastern standard time, which I presume is the time used by Dr. King). There was then nothing unusual about the aurora.
I went out of doors especially for the purpose of ascertaining whether any auroral arch was visible extending from east to west across the zenith; for I observed such a phenomenon here two or three years ago (but without the comet-like appendages described by Dr. King) and have been on the lookout since for its reappearance. Certainly no such arch was visible here at 8:45 p. m. on August 21, and the whole display seemed then to be on the wane. Shortly after 9:00 p. m. only a diffused glow remained in the northern sky above a bank of auroral cloud.
During the course of the night I observed the aurora occasionally to see if there was any change, but noticed nothing unusual until 12:45. The arch might have appeared between 9:00 p. m. and 12:45 without my noticing it, as intervals of at least an hour separated my observations. I can say positively that it did not appear between 12:45 and 2:30 a. m., as I was out of doors continuously watching the sky during that time. From 9:00 p. m. till after midnight I noticed nothing more than the usual faint glow in the north; but happening to glance out of the window at 12:45 I was startled by the tremendous activity then displayed. The maximum was reached about 1:00 a. m., and by 2:00 a. m. the display was practically over. At 2:30 a. m., I returned indoors and made a record of my observations, from which I quote the following extract:
Observing attentively, there seemed to be a luminous streaming upwards from the horizon all around, converging—not at the zenith—but at a point of the sky which I should think would be opposite the sun. I was powerfully impressed by the idea that these were parallel rays directed away from the sun, rendered convergent by perspective.
At the point opposite the sun a considerable space—roughly circular in outline—seemed to be generally free from luminous cloud effects, except when a suffused glow would come and cover the space—a momentary glow without stream effect. Towards the circular space the stream effects were centrally directed all round, being most marked in the northern and northwestern sky, where the stream effects were vivid—luminous pulsations like light smoke driven by a hurricane. The stream effects were much less marked in the western, southern and eastern sky. Light glows would appear, but only by attention could the stream effects be distinguished. I am certain, however, that they were there and that the direction was upwards towards this anti-helial (?) position everywhere.
The appearances noted, were highly suggestive of luminous matter of some sort streaming past the earth on all sides with tremendous velocity in a direction away from the sun—the parallel streams being rendered apparently convergent by perspective.
The aurora, however, is believed to be a strictly terrestrial phenomenon in the nature of an electrical discharge in the higher regions of the atmosphere; although good grounds exist for supposing that there is some intimate connection between great auroral displays on the earth and disturbances going on in the sun.
In this connection it would be interesting to know where Borelli's comet was at the time. It was then rapidly nearing its closest approach to the sun.
|Alexander Graham Bell.|
|Beinn Bhreagh, near Baddeck, Nova Scotia, September 26, 1903.|
MR. COOK ON EVOLUTION, CYTOLOGY, AND MENDEL'S LAWS.
To The Editor: Owing to my absence in Europe, Mr. O. F. Cook's article, published under the above title in the July number of the Popular Science Monthly, has only now come to my attention. Mr. Cook's somewhat drastic criticism of the suggestion regarding Mendelian inheritance, made in my article in the issue of Science for December 19, 1902, takes a prominent place in his essay and relates to a question of wide biological interest. I, therefore, ask space to point out that he failed to grasp the nature of the suggestion; and unfortunately the confusion was worse confounded by his misquotation, of course unintentional, of my own statement in such a way as to make me seem to commit the very error that is the object of his criticism, though I myself had expressly warned against such an error in a paper read before the Washington meeting of the American Association last December!
Mr. Cook's objection to the suggestion, as he understood it and as he quoted it, is perfectly correct, and the man of straw thus set up by his own hand is properly overthrown. Assuredly, to maintain that the reducing division in the maturation of the germ-cells 'leads to the separation of paternal and maternal elements and their ultimate isolation' as 'separate germ-cells' (this as quoted by Mr. Cook, italics mine) involves, as he points out, the reductio ad absurdum that the individual could not show characters individually traceable to more than two grandparents; for this form of statement implies that purely paternal or maternal groups of chromosomes are separated by the division, to be isolated as such in the gametes, the latter being thus rendered pure in respect to parentage. But this, of course, was not my meaning, nor was it what I said. Mr. Cook failed to perceive that my statement referred, not to the parental groups, but to the members of the individual pairs of paternal and maternal chromosomes. What I said was the isolation of the paternal and maternal elements, not 'as' but 'in' separate germ-cells; and the elements thus separated from each other were specifically designated as 'the members of each pair.' I regret that Mr. Cook did not read with greater attention; for my phraseology was carefully chosen, the untenability of the view which is erroneously ascribed to me having been clearly pointed out by Mr. Sutton when he first brought his suggestion to my attention, and since fully considered by him in an article on 'The Chromosomes in Heredity' published in the Biological Bulletin for last April. It is only fair to add that since Mr. Cook accuses me, as he does Mr. Cannon, of a failure to understand the Mendelian principle, it is probable that his misinterpretation arose from the association in his mind of my communication with Mr. Cannon's paper on 'A Cytological Basis of Mendel's Law,' where unfortunately the error in question was not avoided. This paper I first saw after its publication.
In point of fact the cytological evidence on which Sutton based his suggestion leaves quite undecided the question whether any definite order is followed in the grouping of the chromosome-pairs in the equatorial plate, and places no obstacle in the way of assuming that their position is a matter of chance, i. e, that paternal and maternal chromosomes may lie indifferently toward either pole, and that consequently all combinations of paternal and maternal chromosomes may be produced in the gametes. To employ Sutton's graphic illustration: if the number of chromosomes be taken as 8 and designated as A, a, B, b, C, e, D, d (large letters denoting paternal chromosomes and small ones the corresponding maternal), the chromosome-pairs in the equatorial plate might, so far as the cytological evidence shows, present any or all the groupings ABCD abCD aBcD and so on, which gives a possibility of 16 different combinations in the gametes and of 256 in the zygotes or offspring. If the number of chromosomes be 24 (a very common number), the number of possible combinations in the gametes becomes more than 4,000 and in the zygotes nearly 17,000,000 (Sutton). The assumption is, therefore, in full harmony with the fact that offspring may show many different combinations of characters individually traceable to four grandparents or a greater number of more remote ancestors.
Despite the immense range of mixed variation and inheritance thus permitted under the assumption, a point of real difficulty, not touched on by Mr. Cook, is the relatively small number of chromosomes as compared with that of transmissible characters; for if the chromosome-hypothesis, as developed by Sutton, be valid, it would seem to follow that each chromosome stands not for one, but for many, characters, and these should form a coherent group in inheritance. Coherent groups of associated characters have, however, been recognized by many observers, including Mendel himself; and in this direction definite evidence for or against the chromosome hypothesis may perhaps be obtained by the comparative study of variation in nearly related species that differ in the number of chromosomes, though this presents a problem of great complexity. Regarding cases of non-conformity to the so-called Mendelian law or principle, Sutton has endeavored to show that they do not invalidate the suggestions given by the cytological work of himself, Montgomery, Cannon and others. They sufficiently indicate, however, that these suggestions do not yet afford a full or positive explanation, but only, in my own former phrase, give a 'clue' which awaits further development and test. It is entirely possible that the clue may prove false, yet even so it may serve to illustrate that 'fertility of false theories' to which Mr. Cook pays his tribute. In the meantime it is to be regretted that a biologist of Mr. Cook's standing should give currency to the statement that 'The notion that heredity, variation and evolution are the functions of special organs or mechanisms of cells has no ascertained basis of fact' (l. c., p. 222). This 'notion' may be true or false, but such an utterance will be truly surprising to any one having some degree of acquaintance with the literature of embryology and cytology.
|Edmund B. Wilson.|
|September 24, 1903.|