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THE POPULAR SCIENCE MONTHLY. 



tified ; also a list of such telescopic objects 

 in each constellation as are easily found, and 

 lie within the power of a small telescope. 

 The volume is illustrated with one hundred 

 and fifty-eight cuts. 



American Spiders and their Spinning-Work. 

 Vol. I. By Henry C. McCook, D. D. 

 Published by the Author: Academy of 

 Natural Sciences, Philadelphia. Pp. 372. 

 Price $30 (set of three volumes). 



The naturalist who takes dried or alco- 

 holic specimens as the subjects of his study 

 can prosecute his researches at all times and 

 seasons, and independently of the will of the 

 creatures that he is studying. But this ad- 

 vantage is offset by the limitation that the 

 habits of the creatures, the kind of places 

 they live in, the sort of structures they make, 

 the way they move about, obtain their food, 

 and rear their young, are a sealed book to 

 him. The observations of the field natural- 

 ist, on the other hand, are attended by many 

 more difficulties than those of the laboratory 

 student. He must go to his specimens in- 

 stead of having them brought to him. Per- 

 haps they are not to be found at all seasons, 

 and, when they are accessible, many hours 

 must be spent in watching familiar actions 

 in order not to miss a chance of seeing a 

 new operation. He has the compensation, 

 however, that he studies the creatures alive ; 

 hence the things which are hidden from the 

 laboratory naturalist are revealed to him, 

 and the knowledge that he gains arouses the 

 widest interest and wins the greatest appre- 

 ciation. The results which Dr. McCook lays 

 before us in the present volume belong 

 mainly in the latter class. They relate to 

 the spinning-work of spiders, as performed 

 in the making of webs and dens. With this 

 is naturally connected some account of the 

 methods of procuring food and the nesting- 

 habits of these creatures, and the intelli- 

 gence that they display in adapting their 

 operations to particular circumstances. In 

 order to give the reader a correct idea of 

 how spiders form their threads, a fully illus- 

 trated chapter on the structure of the spin- 

 ning-organs has been introduced. The whole 

 work will be confined to the orb-weavins: 

 spiders of the United States, but a vast 

 amount of material relating to other tribes, 

 which the author has collected, has been 

 drawn upon in order to make comparisons 



between the habits of the orb-weavers and 

 other spiders. To the general reader, who 

 sees no important difference between any 

 two common wheel-shaped spider-webs, the 

 distinct varieties of orb-weavers' snares de- 

 scribed by Dr. McCook will be a revelation. 

 Artists, too, who are supposed to be careful 

 about the correct shapes of the things they 

 draw, seem to have looked only carelessly at 

 spiders' webs, for our author states that he 

 has never seen but one in art work or book 

 illustrations that gave proof of having been 

 drawn from a natural web, by one who knew 

 its characteristics. In three chapters the 

 general features, the mode of constructing 

 in detail, and the armature of orb-webs 

 are presented. Passing to varieties of 

 the orb, Dr. McCook describes the web 

 with its center of closely woven silk tis- 

 sue and a zigzag ribbon extending upward 

 and downward, which is made by Argiope, a 

 spider whose large size and beautiful mark- 

 ings make it conspicuous in our autumn 

 fields. The round vertical webs made by 

 Epe'ira and other spiders are then touched 

 upon. An account is given of the composite 

 snares, which consist of a wheel-shaped web 

 combined with a maze of intersecting lines ; 

 also of the sectoral orb, in which there is 

 always one division of the wheel that is not 

 crossed by the concentric rings. 



Among the other peculiar features in webs 

 that the author describes are the domed orb 

 of the basilica spider, the ribbon decorations 

 of the feather-foot, the triangle or part of a 

 circle constructed by the triangle spider, and 

 the somewhat irregularly radiating snare of 

 the ray spider. A chapter on the engineer- 

 ing skill of spiders gives instances of their 

 using weights to hold their webs taut, their 

 placing of stay -lines in the best position al- 

 lowed by circumstances, using unfamiliar 

 substances for building a nest, etc. Espe- 

 cially interesting is a chapter on the me- 

 chanical strength of webs and the physical 

 power of spiders, in which cases are given 

 of spiders capturing and hoisting from the 

 ground animals many times as large as them- 

 selves. Other topics that are fully treated, 

 but which can be only mentioned here, are 

 feeding habits, uses of poison, and nest- 

 making habits. In a concluding chapter on 

 the genesis of snares, the author traces the 

 relations which exist between the various 



