FRAGMENTS OF SCIENCE.
as he could draw well he was ordered to decorate the mausoleum of the Mahdi, and this pleased the women of the Khalifa so much that they petitioned the latter for his liberation. It is also said that he has written Arabic books and illustrated them. The latter part of his twelve years' detention appears to have been less onerous, as after the escape of Slatin he had to be interpreter to the Khalifa and translator of European newspapers which the ruler of the Soudan received regularly. It is to the credit of the Khalifa Abdullahi that not one of the Christian prisoners received a hurt on the approach of the Anglo-Egyptian forces. It is expected that a narrative of his experience in the Soudan will be shortly published by Dr. Neufeld."
Natural Selection and Fortuitous Varia- tion — The three principal objections urged against Darwin's theory of natural selection were stated by Prof. W. F. R. Weldon, in his presidential address to the Section of Zoology and Physiology of the British Asso- ciation, as being that the species of animals we know fall into orderly series for the selection of which purely fortuitous varia- tions can not be supposed to afford opportu- nity ; that minute structural variations can not be supposed to affect the death-rate so much as the theory requires they should, while many of the characters by which spe- cies are distinguished appear to us so small and useless that they can not be supposed to affect the chance of survival at all ; and that the process of evolution by natural selection is so extremely slow that the time required for its operation is longer than the extreme limit of time given by estimates of the age of the earth. The first of these objections the speaker alleged to be due to a misunder- standing of words ; we regard as fortuitous what we do not understand ; and he proceeded to explain how what we call chance may be shown, especially by a method developed by Professor Pearson, to be a real and important factor. To the other two objections Pro- fessor Weldon opposed the results of ob- servations of his own and of Mr. Herbert Thompson on the small shore crabs ( Carci- nus mcenas) at Plymouth Beach. " In these crabs small changes in the size of the fron- tal breadth do, under certain circumstances,
��affect the death-rate ; and the mean frontal breadth among this race of crabs is, in fact, changing at a rate sufficiently rapid for all the requirements of a theory of evolution." In conclusion, he said : " I hope I have con- vinced you that the law of chance enables one to express easily and simply the fre- quency of variations among animals, and I hope I have convinced you that the action of natural selection upon such fortuitous varia- tions can be experimentally measured, at least in the only case in which any one has attempted to measure it. I hope I have convinced you that the process of evolution is sometimes so rapid that it can be observed in the space of a very few years." The whole difficulty of natural selection, he added, is a quantitative difficulty ; and he insisted upon the need of observations and measurements of the rates of variation.
The Interior of Canada. — The country between Lake St. John and James Bay is under survey by the Department of Coloni- zation and Mines of Quebec, in furtherance of a scheme for a transcontinental railroad to tap the Hudson Bay country and Lake Winnipeg. As to the commercial advan- tages of a railway center established at the head of James Bay or at the limit of tide water on the Nottaway River, Mr. O'Sullivan, the surveyor, shows that the shore line of Hudson and James Bay, following the east coast from the mouth of the Nottaway to the southern entrance to Hudson Strait, measures, in a line running due north, eight hundred miles, or about the same distance as the former point is north of the city of Washington ; and the western shore line, measured in the same way to Rowe's Wel- come, is about sixteen hundred miles, while the area inclosed amounts to more than three hundred and fifty thousand square miles. While Hudson Strait is blocked with ice during nine months of the year, the bay itself is navigable from June till Novem- ber, and James Bay is generally open early in May. All the large rivers — the Albany, Moose, Hannah, Nottaway, Rupert, Main, and Big Rivers — converge along these shores, and the forest wealth of the thousands of miles drained by these and lesser rivers can be concentrated at the mouth of the Nottaway or Rupert. The land along the line from Lake