May 8, 1885.] 



♦ KNOWLEDGE ♦ 



389 



THE COCOOX OF A SPIDER. 



AT a recent meeting of tlie Academy of Natural 

 Scier.ces, of Philailelpliia, Pr. H. C. :Mcrook stilted 

 that, while walking iu the suburVis of Philadelphia lately, 

 he had found under a stone a female Lyoosa, proliaMy /.. 

 riparia, Hentz, which he placed in a jar partly tilled with 

 dty earth. For two days the spider remained on the 

 surface of the soil, nearly inactive. The earth was then 

 moistened, whereupon she immediately began to dig, con- 

 tinuing until she had made a cavity about one inch in 

 depth. The top was then carefully covered over with a 

 tolerably closely woven sheet of white spinning work, so 

 that the spider was entirely shut in. This cavity was 

 fortunately made against the glass side of the jar, and the 

 movements of the inmate were thus exposed to view. 

 Shortly after the cave was covered the spider was seen 

 working upon a circular cushion of beautiful white silk 

 about three-fourths of an inch in diameter, which was spun 

 upward in a nearly perpendicular position against the 

 earthen wall of the cave. The cusliion looked so much 

 like the cocoon of the common tube weaver, AyaJena 

 ruevia, and the whole operations of the lycosid were so 

 like those of that species when cocooning, that it was 

 momentarily supposed tliat a mistake in determination had 

 been made. 



After the lapse of half an hour, it was found that the 

 spider had o\-iposited against the central part of the cushion, 

 and was then engaged in enclosing the hemispherical egg- 

 mass with a silken envelope. The mode of spinning was as 

 follows : the feet clasped the circumference of the cushion, 

 and the body of the animal was slowly revolved ; the abdo- 

 men, now greatly reduced in size by the extru-sion of the 

 eggs, was lifted up, thus drawing short loops of silk from 

 the expanded spinnarets, which, when the abdomen was 

 dropped again, contracted, and left a flossy curl of silk at 

 the point of attachment. The abdomen was also swayed 

 backward and forward, the filaments from the spinnarets 

 following the motion as the spider turned, and thus an even 

 thickness of silk was laid upon the eggs. The same be- 

 haviour marked the spinning of the cushion, in the middle 

 of which the eggs had been deposited. The ideas of the 

 observer as to the cocooning habits of Lycosa were very 

 much confused by an observation so opposed to the universal 

 experience. Upon resuming the study after the lapse of 

 an hour and a half, he was once more assured of being right 

 by the sight of a round silken ball dangling from the apex 

 of the spider's abdomen, held fast by a short thread to the 

 spinnarets. The cushion, however, had disappeared. The 

 mystery, as it had seemed, was solved ; the lycosid, after 

 having placed her eggs in the centre of the silken cushion 

 and covered them over, had gathered up the edges, and so 

 united and rolled them as to make the normal globular 

 cocoon of her genus, which she at once tucked under her 

 abdomen in the usual way. 



This was a most interesting observation, which Dr. 

 McCook believed had not before been made. The manner 

 of fabrication of the cocoon of Lycosa had been heretofore 

 unknown to him, and, by reason of her subterranean habit, 

 the opportunity to observe it was of rare occurrence. He 

 had often wondered how the round egg-ball was put 

 together, and the mechanical ingenuity and simplicity of 

 the method were now apparent. The period consumed in 

 the whole act of cocooning was less than four hours ; the 

 act of ovipositing took less than half an hour. Shortly 

 after the egg-sac was finished, the mother cut her way out 

 of the silken cover. She had evidently thus secluded 

 herself for the purpose of spinning her cocoon. 



Dr. ilcCook also alluded to another interesting fact in 



the life history of the Ijycosa, which had been brought to 

 his attention liy ^Nlr. Alan Gentry. A shib of ice having 

 been cut from tiic frozen surface of a pond about eight or ten 

 feet from the bank, several sjiiders were observed running 

 about iu the water. 1'hey were jiassing underneath the 

 surface, between certain water plants. It is remarkable to 

 find these creatures thus living in full health and activity 

 in mid-winter, within the waters of a frozen pond, and so 

 far from the bank in which the burrows of their congeners 

 are commonly found. It has been beliovinl heretofore, and 

 doubtless it is generally true, that the lycosids winter in 

 deep burrows in the ground, sealed up tightly to maintain 

 a higher temperature. — Scientific American. 



CHAPTERS ON MODERN DOMESTIC 

 ECONOMY. 



XXVI.— THE FRAMEWOHK OF THE DWELLING-HOUSE. 



STRUCTURAL EX.\MPLES {COntimied). 

 THE DISPOSAL OP HOUSEHOLD 15EFUSE. 



AS a general rule, the traps and soil-pipes of a house 

 are made of metal, and are hence, .sooner or later, 

 liable to corrosion ; the destructive influence of sewer- 

 gases is moat manifest at angles or sharp bends. An 

 ordinary, well-ventilated leaden soil-pipe will last from 

 18 to 30 years ; an unventilated pipe of the same material, 

 drawn, and not soldered, .succumbs after from 8 to 'M 

 years. Iron pipes do not last so long, and zinc is to bo 

 condemned altogether, since its use leads to most uncertain 

 and invariably bad results ; facts which are attested to by 

 many examples now deposited in the Parkes' Museum of 

 Hygiene. From these memoranda our readers will conclude 

 that stoneware traps and pipes ought always to be sub- 

 stituted, especially as we have already given excellent 

 examples in former chapters ; but stoneware pipes and 

 traps are not always easily procurable, and, when so, are 

 oftentimes left alone by the metal-working plumber, whose 

 name is not .amiss since he likes to work most of all with 

 lead. Hence the necessity has aiisen for leaden articles of 

 dependable value, since they can be easily applied to the 

 wants of the majority of existing cases. 



Last week we gave a brief description of the prevalent 

 and most defective so-called " D-trap," which is now con- 

 demned by the model laws of the Local Government 

 Board ; it remains for us to point out what ought to be 

 done in case one of our readers should find such a structure 

 in his house. He may with safety remove it, and place in 

 the gap an ordinary " S-trap," or a " Half-S-trap," com- 

 monly known as a " P-trap." There are a great many 

 makers of these traps ; but, for the reasons we have stated 

 above, it would be found that the views of the reader and 

 his plumber are likely to be both agreeably met if some 

 firm were to construct traps out of lead in such a 

 way as to resist the action of sewer-gases for such 

 a length of time that the trap may prove to be 

 really economical and safe. Messrs. Beard <fe Dent 

 have taken upon themselves this task with .a suc- 

 cessful issue ; their traps are made of the softest and 

 purest pig-lead, without any seam or solder ; they are 

 perfectly smooth both within and without, and arc; so 

 strong that each superficial foot of the trap contains no less 

 than 8 lb. of metal. Perhaps, however, the best trap now 

 made of the class of substitutes which we are now com- 

 menting upon is Hellyer's patent cast-lead " Anti-D Trap." 

 It is made upon the principles we have just quoted, but 

 has a decided advantage in shape, which may be likened to 



