164 



NATURAL SCIENCE NEWS. 



shaft is covered wifh a silken pa- 

 per lining, spun from the animal's 

 spinnarets. 



The door at the top of the shaft 

 is made of several alternate layers 

 of silk and earth, and is supplied 

 with an elastic and ingenious 

 hinge, and fits closely in a groove 

 around the rim of the tube. This 

 door simulates the surface on 

 which it lies, and is distinguish- 

 able from it only by a careful 

 scrutiny. The clever spider even 

 glues earth and bits of small plants 

 on the upper side of his trap-door, 

 thus making it closely resemble 

 the surrounding surface. 



The spider generally stations it- 

 self at the bottom of the tube. 

 When, by tapping on the door, or 

 by other means, a gentle vibration 

 is caused, the spider runs to the 

 top of his nest, raises the lid, and 

 looks out and reconnoitres. If a 

 small creature is seen, it is seized 

 and devoured. If the invader is 

 more formidable, the door is quick- 

 ly closed, seized and held down by 

 the spider, so that much force is 

 required to pry it open. Then, 

 with the intruder looking down 

 upon him, the spider drops to the 

 bottom of the shaft. 



A young friend of mine has 

 spent much time lately watching 

 and investigating the operations of 

 this spider. He found by many 

 experiments — all with the same re- 

 sult — that when the door of his 

 nest is removed, the spider can re- 

 new it five times — never more than 

 that. Within these limitations, 

 the door torn off in the evening 

 was found replaced by a new one 

 in the morning. Each successive 

 renewal showed, however, a great- 

 er proportion of earth, and a small- 

 er proportion of silk, until, finally, 

 the fifth door had barely enough 

 silk to hold the earth together. 

 The sixth attempt, if made, was a 

 failure, because the spinnarets had 

 exhausted their supply of the web 

 fluid. When the poor persecuted 

 spider finds his domicil thus, open 

 and defenceless, he is compelled 

 to leave it, and wait until his stock 

 of web fluid is renewed. 



From forty to fifty cream-color- 

 ed spiderlings are hatched from 

 the yellow eggs at the bottom of 

 the nest. When these have at- 

 tained only a fraction of their full 

 size — before they are half grown — 

 their affectionate mother drives 

 them out into the world to shift 

 for themselves. After a brief pe- 

 riod of uncertainty, they begin ac- 

 tive life by making nests, each for 

 itself, generally close to "the old 

 homestead," sometimes within a 



few inches of it. These nests are 

 always shallow and slender, and 

 are soon out grown. When the 

 spider attains its full size it con- 

 structs a larger nest. 



The spider is seldom seen out- 

 side of its nest, which it rarely 

 leaves — during the day, at least, 

 and then only for a few minutes, 

 and for a short distance. Upon 

 any alarm, it hastens to its nest, 

 lifts the door, which quickly 

 springs back into its place, and is 

 held down by the householder un- 

 til the alarm has subsided. 



I now have a large nest, con- 

 taining a mother and. her yellow 

 spiderlings, which I am carefully 

 watching and studying. — -D. Cleve- 

 land, San Diego, Calif, in Science. 



A Fish's Bladder. 



Naturalists long ago studied the 

 composition of the gas contained 

 in the swimming bladder of fishes 

 and discovered that it consists of 

 the principal constituents of the 

 air — namely, oxygen, nitrogen and 

 carbonic acid. But these constit- 

 uents are not mingled in the fish's 

 balloon in the same proportions as 

 they are in the atmosphere, and 

 besides their proportions do not 

 remain always the same in the fish. 

 Sometimes the bladder contains 

 hardly any oxygen; at others oxy- 

 gen-constitutes nine-tenths of the 

 whole contents. 



The variation in the quantity of 

 oxygen is somewhat mysterious, 

 and naturalists have offered sev- 

 eral different suggestions as to the 

 cause of it. Some think the fish 

 may be able to control the quantity 

 of oxygen in the bladder by its 

 own will. Biot, a distinguished 

 French naturalist, thought he had 

 solved the problem by discovering 

 that the proportion of oxygen was 

 larger in fish that lived at great 

 depths and smaller in those that 

 lived near the surface of the sea. 



But quite recently new observa- 

 tions made from the Prince of Mo- 

 naco's yacht, Princess Alice, seem 

 to prove that Biot was mistaken 

 and that the deep dwelling fish 

 carry no more oxygen in propor- 

 tion than do those living in shallow 

 water. Some of the fish whose 

 swimming bladders were examined 

 by the naturalist on the Princess 

 Alice came from a depth of no 

 less than a mile. 



They were compared with fish 

 which seldom descend below 200 

 feet in depth and with others which 

 prefer a depth of about 500 or 600 

 feet, and all had nearly the same 



proportion of oxygen to aid them 

 in swimming. •"' 



The variations mentioned above 

 seem therefore to depend upon 

 some other cause than the depth 

 of the fish's dwelling place. 



It is these unsettled questions 

 that offer to young naturalists some 

 of their most brilliant opportuni- 

 ties for distinction. It is a great 

 mistake to suppose that there does 

 not remain a plenty of'iroom for 

 discovery in science. — Youth's Com- 

 panion. 



The Poison of the Ornitho- 

 rhynchus. 



The hind feet of the ornitho- 

 rhynchus; "the mole with webbed 

 feet and the bill of a duck" that 

 puzzled zoologists so much for a 

 long time, are provided with a sol- 

 id spur connected with a gland. 

 Have we here a poison gland? 

 From some apparently trustworthy 

 accounts that have reached him, 

 Mr. Stewart thinks we have. This 

 gland is at least venomous at a 

 certain season. A dog was wound- 

 ed by one of these spurs three 

 times, and the symptoms the first 

 time were those of pain and som- 

 nolence, but there were no con- 

 vulsions, titubations or trembling. 

 Upon the other two occasions, the 

 symptoms were less pronounced, 

 and even null, thus indicating hab- 

 ituation. The poison has proved 

 mortal to the dog in' four cases, 

 but in man the symptoms disaap- 

 pear without causing death. — Sci- 

 entific American. 



The Arawaks. 



In the Port Royal Mountains, 

 Jamaica, an interesting archaeolog- 

 ical discovery was recently made 

 of a cave containing the skeletons 

 of at least twenty-four of the aborig- 

 inal Arawaks. When Columbus 

 discovered the island in 1494 the 

 Arawaks were estimated at about 

 600,000. A century and a half 

 later, on the capture of Jamaica 

 by the English, they had com- 

 pletely disappeared, even to their 

 bones, as only the skulls until now 

 had been found. These showed a 

 frontal depression with lateral ex- 

 pansion, an artificially formed de- 

 formity that is also found in those 

 just discovered, which are of all 

 ages. A shattered canoe of cedar 

 wood, 7 feet long and \y 2 feet 

 wide, an arborvitse mortar, and two 

 earthenware vessels were found 

 with the skeletons.- — Scientific 

 American. 



