March 20, 1891.] 



SCIENCE. 



159 



away and burn the black excrescences. If a tree is badly at- 

 tacked, the wise method is to out down bodily, and destroy it by 

 fire., Finally, when once the old knots are cleared out, it will be 

 an easy matter to keep the fungus from gaining a fresh foothold. 

 There are many trees which are literally covered with knots, and 

 have been for years, — -trees which bear no fruit, and never will, 

 — and they are worse than mere monuments of carelessness, for 

 they propagate and perpetuate a disease that renders plum-raising 

 almost an impossibility in their neighborhood. Sometimes these 

 old, distorted trees are on the roadside, where any passing lad 

 can pull oS and carry to his own home one of these malforma- 

 tions, to become a new centre of infection. But these knots do 

 not need to be transported to produce infection, for the millions 

 of spores developed in the spring, while too small to be seen, pass 

 long distances with the winds, and thus spread the disease. 

 There are several fungous diseases against which the State Legis- 

 latures or the National Congress might pass enactments fully as 

 wholesome and beneficial as those for the control of the diseases 

 of animals; but few of them offer so many favorable points for 

 successful legislation as the black knot, — the scourge of plum and 

 cherry growers in many localities. The law should include, to be 

 eflfective, all wild plum and cherry trees that are breeding-places 

 of the pest." 



— Mr. E. H. Hankin of St. John's College, Cambridge, En?.. 

 is said to have discovered a cure for anthrax, to the study of 

 which disease he has devoted himself many years. He based his 

 investigations, according to Hardwicke's Science-Qossip, upon the 

 principle of lymph inoculation, which Dr. Koch has so success- 

 fully applied in the case of tuberculosis. The glycerine extract in 

 Mr. Hankin's process is precipitated with alcohol, and re-dissolved 

 in water. The experiment has been repeated on a number of 

 subjects with gratifying success. This discovery derives addi- 

 tional interest from the fact that anthrax is not the only disease 

 from which rats (the spleen of which animal produces the pro- 

 tective proteid) enjoy immunity. 



— An insect which is not uncommon in India is a medium-sized 

 mantis, between three and four inches in total length. It is one 

 of those mantises, says Mr. J. R. Holt in Science-Qossip for March, 

 which have a long slender thorax, and which, owing to the second 

 and third pairs of legs being very long, carry their thorax and 

 head very high. In this insect the thorax is about half its entire 

 length, and is of a bright grass-green color, without any markings, 

 and it obviously mimics a grass-stem. The abdomen is aiso some- 

 what slender; the wisg-covers are of a grass green color, without 

 markings; and it obviously mimics a grass-blade. But in both 

 these cases the mimicry is obvious, as also the reason for it, and 

 it is not what Mr. Holt would call attention to. The first joint of 

 the fore-legs is widened and flattened ; it is also green, and the 

 posterior surface is marked with a lai'ge ocellus. When the insect 

 is undisturbed, it remains generally in one place, but is not per- 

 fectly motionless : it sways perpetually and uniformly from side 

 to side. In this position it luoks very harmless, but if it is startled 

 or alarmed its a-pect instantly changes: it partly opens the wings, 

 turns its head and thorax so as to face the terrifying object, makes 

 a noise like a sudden, sharp puff of wind, very like the noise made 

 by a startled snake, and raises its fore-legs so that the first joint 

 lies along the thorax; and, the inside margin of the expansion 

 being nearly straight, it looks as if the fore-legs and thorax were 

 connected. In this position the ocelli are very conspicuous, and, 

 with the small, triangular head and the slender thorax, the effect 

 is to produce a ludicrous resemblance to a diminutive cobra. Now, 

 what puzzles one, is this exact resemblance. The insect could not 

 possibly be taken for a cobra on account of its small size and green 

 color; while, if the object is only to appear formidable, it could 

 have been obtained without imitating a cobra so exactly. It may 

 be suggested that there is no direct imitation, but that the same 

 causes which have led to the development of the eye spots in the 

 cobra have also led to the development of ocelli in this insect, viz., 

 that the apparent possession of a large head gives the animal a more 

 formidable appearance; but this explanation is apparently nega- 

 tived by the peculiar noise made by the insect, which certainly 

 seems to indicate that a snake is imitated. Possibly the object of 



the noise is to suggest that it is some kind of snake, and then the 

 ocelli may suggest that it is one of the cobra kind. Maybe some 

 of our readers may be able to suggest a better explanation. Any- 

 how, the thing is curious, and worthy of note. 



— There is now direct telephone communication between Lon- 

 don and Paris. The first conversation between the two cities was 

 exchanged on March 17, and, according to press despatches, the 

 results were highly satisfactory. 



— The Illinois Experiment Station is located on a black loam 

 about twenty inches deep, underlaid with clay, — the soil common 

 to the prairies of Illinois. Thus located, that station is wisely de- 

 voting much of its resources to the study of the great cereal crop, 

 corn. In Bulletin No. 13, for February, 1891, is given a detailed 

 report of the experiments of corn made at that station for 1890, 

 with a summary of the results for 1888 and 1889. The results 

 may be summarized as follows: Of the varieties of corn treated, 

 the medium maturing sorts (such as Learning, and white varieties 

 of similar season) are recommended for central Illinois. These 

 have given a higher yield, without exception, than those maturing 

 earlier or later. Good crops of com were raised from a medium 

 maturing variety when planted any time in May. Planting at 

 about one inch in depth has been followed by larger crops on the 

 average than deeper planting. Corn planted at the rate of one 

 kernel every twelve inches, in rows three feet eight inches apart, 

 gave a larger average yield of grain than when planted either 

 thicker or thinner. Better results were obtained from planting 

 in hills than in drills, apparently because in hill-culture the corn 

 could be kept cleaner. No appreciable benefit has been derived 

 from frequent cultivation, nor from cultivation after the ordinary 

 time. For the three years the yield has been increased to the ex- 

 tent of one-fourth by shallow cultivation. The plat which had no 

 cultivation after planting, except to remove the weeds by scraping 

 with a sharp hoe, yielded more each season than the average of 

 the deep cultivated plats, and in but two instances did any one of 

 the deep cultivated plats yield more than the plat not cultivated. 

 These experiments indicate that any cultivation of the soil which 

 effectually removes the weeds, and at the same time disturbs the 

 roots as little as possible, is the best; and that on this soil the 

 stirring of the ground beyond what is necessary to kill the weeds 

 is of little if any benefit. No practical benefit was received from 

 the use of commercial fertilizers. The increased yields from the 

 use of stable manure probably repaid the cost of the application, 

 and left some profit. 



— In a recent bulletin of the Geological Society of America, 

 Robert Bell, M.D., assistant director of the Geological Survey of 

 Canada, describes the nickel and copper deposits of Sudbury dis- 

 trict, Canada. There is also an appendix on the silicified glass- 

 breccia of Vermilion River, Sudbury district, by Goorge H. Wil- 

 liams. The town of Sudbury, a creation of the Canadian Pacific 

 Railway, is situated in the backwoods of Ontario, thirty-six miles 

 north of the mouth of French River, on Lake Huron. Other 

 metals, including gold, platinum, tin, lead, silver, zinc, and iron, 

 have been found in the Sudbury district, and probably some of 

 them may prove to exist there in paying quantities. The presence 

 of a considerable proportion of nickel in the ore of the Wallace 

 mine, on the shore of Lake Huron, and in the strike of the Sudbury 

 deposits, was ascertained by Dr. Hunt more than forty years ago; 

 yet the presence of this metal in the latter does not seem to have 

 been suspected for a considerable time after they had been worked 

 for copper alone. The Huronian is notably a copper-bearing sys- 

 tem. West of Sudbury, this metal occurs around Batchawana 

 Bay, north of Sault Ste. Marie, at Little Lake George and Echo 

 Lake, at Huron Copper Bay, in Wellington and Bruce mines, on 

 Thessalon and Mississagui Rivers, and elsewhere. To the north- 

 eastward it has been found on both sides of Lake WahnapitEB. on 

 Temagami and Lady Evelyn Lakes, along Montreal and Blanche 

 Rivers, on the watershed east of the canoe route between Lakes 

 Temiscaming and Abbittibi, and finally near the southern ex- 

 tremity of Lake Mistassini. The search for this metal along the 

 Huronian belt is only in its infancy, and the copper-mining in- 

 dustry may some day be very extensively carried on in various 

 parts of this as yet almost unknown section of Canada. 



