340 



SCIENCE. 



[Vol. XVIII. No. ^('S. 



pears, about an inch to tbe left, part of the same column, small, 

 and tbe black, under ariiticial light, like weak purple. The right- 

 hand side of this ghostlike column is lost to the right eye, being 

 commingled with the larger, darker lettei-s seen by the short- 

 sighted left, which cover it like the more recent writing on a 

 palimpsest. Middle life was reached before the discovery was 

 made. These experiences must be gone through with intent, for 

 objects generally being perceived altogether with the right eye, all 

 that the left seems good for is to supply a little more light. The 

 perception of the difference of color is as good with the one eye as 

 the other, and the short-sighted eye can read pmaller type. As the 

 inferior animals, so far as I know, have no habit of peeping or look- 

 ing 'with one eye shut and the other open, it occurred to me that this 

 ability might be a limited one. I tried the experiment with school 

 children, and to ray surprise found that a few were quite unable 

 to keep one eye shut and the other open at the same time, and a 

 few did it with an effort, making in all about a fourth of the 

 number. Adults were likewise under similar limits, but to a less 

 extent. This may be the reason why the discovery of inequality 

 of vision, as Sir John Herscbel remarks, is often made late in life. 

 Indeed, he mentions an elderly person who made the unpleasant 

 discovery that he was altogether blind of an eye." 



— The University Extension Conference in Toronto, on Nov. 5-6, 

 led to the establishment of the Canadian Society for the Extension 

 of University Teaching, the organization of which is largely 

 modelled on that of the American Society. The Univer- 

 sities of Ontario and Quebec were thoroughly represented and the 

 leading colleges, normal schools, and high schools of the Domin- 

 ion sent delegates. President James of the American Society 

 gave the leading address on the evening of Nov. 5, and was pres- 

 ent at the different sessions to explain the various questions that 

 arose. The presidents of the new society are Sir Donald A. Smith 

 of Montreal, Chancellor G. W. Allen of Trinity, Chancellor Ed- 

 ward Lake of Toronto University, Professor Goldwin Smith, 

 Chancellor Sanford Fleming of Queen's, and Abbe Laflamme of 

 Laval University. The secretary is Mr. William Houston of To- 

 ronto, the well-known economist, to whom is due in large meas- 

 ure the success of the meeting and the establishment of the soci- 

 ety. 



• — The following is an abstract of a bulletin on " The Hessian 

 riy," recently published by Professor F. M. Webster, consulting 

 entomologist to the Ohio experiment station. This fly is a small, 

 dark-colored, tsvowinged fly, about one-eighth of an inch 'ong 

 and shaped much like the wheat midge, both belonging to the 

 same order and family of insects. The male is more slender than 

 the female, which, when full of eggs, slightly resembles a dimin- 

 utive mosquito moderately full of blood. The life of the insect 

 in the adult stage is short, the male dying socn after pairing and 

 the female soon after oviposition. The egg is about one-fiftieth 

 of an inch long, of a dull reddish color. The larva or maggot is, 

 when first hatched, of a nearly white color, with a tinge of red, 

 but later they are very light green, clouded with white. The 

 pupa is formed under cover of the puparium, which last is known 

 as the "flaxseed" stage, on account of its resemblance to a flax- 

 seed in form and color. The insect is best known under this 

 name and in this stage of development. The eggs are deposited 

 by the female very soon after she hatches from the " flaxseed," 

 as the rule, on the upper side of the leaf. This task is finished 

 in a few days, after which she dies. The young hatching from 

 the egg works its way downward, beneath the sheath to its base. 

 In the fall this is just above the roots below ground, but in spring 

 they do not go below ground, as a rule, but stop at or near one of 

 tlie lower joints. It is proper to say that this pest suffers much 

 from the attacks of several minute parasites, which attack and 

 destroy it in both the egg and larval or maggot stage. There are 

 two annual attacks of the Hessian fly, one appearing in the fall 

 and the other in the spring. With the fall brood the time of de- 

 positing the eggs varies with the latitude, the farther north the 

 locality the earlier the time of egg laying. In northern Ohio the 

 eggs are deposited early in September, while in the southern part 

 this is delayed until probably early in October, the grain over the 

 territory between these points being stocked with eggs between 



the dates given. Whether there is the same variation with re- 

 spect to the spring brood is not known. The eggs at this season 

 are deposited in April and May, the insect usually reaching th& 

 " flaxseed " stage before harvest and remaining through July and 

 August in the stutible. The preventive measures may be noticed 

 as follows: Sowing at the proper time; burning of the stubble; 

 rotation of crops; sowing long, narrow plats in late summer as 

 baits; applying quick acting fertilizers to seriously infested fields 

 in the fall in order to encourage attacked plants to throw up fresh 

 tillers, and to increase the vigor of these that they may make 

 sufficient growth to withstand the winter. After the fly has 

 gained possession of a field Professor Webster knows of no appli- 

 cation that can be made which will destroy it. Doubtless pas- 

 turing the field, if early sown, will often result in reducing the 

 numbers of the pest, besides giving to the ground that compact, 

 pulverized nature which it should have had at first. No doubt 

 many larvae and "flaxseeds "by this means would be crushed, 

 but vtry few would enter into the food of the anima's grazing- 

 thoreon, unless the plants were pulled up both stem and roots. 

 Sheep are probably the best animals to turn on wheat as they are 

 not heavy enough to injure plants by trampling. 



— The work of university extension lias been undertaken in 

 Australia by the University of Melbourne. There are at present 

 nineteen lecturers on the list whose courses include a wide range of 

 subjects in the departments of history, literature, art, philosophy, 

 and science. It is claimed that while the work will suffer under 

 certain disadvantages as compared with England, the rtual popu- 

 lation being scantier and less compact, and tbe means of commu- 

 nication not so good, the average Victorian has greater means 

 and more leisure at bis disposal than the average Englishman. 

 Certainly the Australians are not a people lacking cither in energy 

 or in quickness to avail themselves of whatever advantages may 

 come within their reach. It is interesting to note another illus- 

 tration of the analogy between Australian and American devel- 

 opment in the adoption of the short course of six lectures. With 

 the success of the work, however, tbe tendency to longer courses 

 will certainly appear in Australia as it has already done in the 

 United States. 



— On Dec. 3, Mr. G. H. Robertson read before the Loudon So- 

 ciety of Arts a paper on "Secondary," or, as he prefers to call 

 them, " Reversible Batteries," which is reported in Engineering. 

 After giving the history of their inventiou and improvement, he 

 reviewed tbe chemical changes which tako place in the acid, this 

 being a subject to which he has devoted very great attention. 

 Plante considered thaftbe variations in electromotive force were 

 due to the formation of peroxides in the acid. Messrs. Gladstone 

 and Tribs, testing the acid between the plates, alwaj s found traces 

 of something which decolorized permanganate, and might there- 

 fore be hydrogen dioxide or ozone. In 1878 Berthelot discovered 

 persulphuric acid (HjSaOg), and showed it was the primaryprod- 

 uct of the electrolysis of sulphuric acid solution, and that the 

 hydrogen dioxide present in sulphuric acid after electrolysis is 

 due to the action of that body on the acid. Persulphuric acid be- 

 gins to decompose as soon as the current is stopped, and its de- 

 composition is accompanied by the formation of hydrogen diox- 

 ide, unless the acid is too dilute. BIr. Robertson found that when 

 "cells were tested they contained active oxygen, due to the pr-esence 

 of persulphuric acid and peroxide of hydrogen in varying propor- 

 tions. Diu:ing charge persulphuric acid is the main constituent; 

 during discharge the quantity of hydrogen dioxide gradually in- 

 creases; while in a cell that has been at rest some time there is 

 very little except hydrogen dioxide to be found. Active oxygen 

 forms at once on the passage of the current, decreases slightly, 

 and then increases to a little above its first value. Starting either 

 charge or discharge always causes initial increase, except in the 

 case of cells which have been long idle, when there is a diminu- 

 tion due to the decomposition of the excess of hydrogen dioxide 

 in the acid. Persulphuric acid does not itself reduce peroxide of 

 lead, but it foims hjdrogen dioxide ou standing, and this is capa- 

 ble either of oxidizing the lead plate to litharge, or of reducing 

 the peroxide plate to the same substance. In each case the 

 litharge is converted into sulphate by the sulphuric acid. This 



