HARDWICKE'S SCIENCE- GOSSIP. 



which are bent in the nature of claws, are very 

 similar to the sting of the scorpion and fangs of 

 millepeda ; and in each of these fangs (for so I will 

 call them) is a small aperture, through which in all 

 probability a liquid poison is emitted by the spider 

 at the time it inflicts the wound." 



Leeuwenhoek's discovery was disputed by some 

 of the learned men of the day. Dr. Mead, in his 

 "Essay on Poisons," doubted the fact, in which he 

 was at first supported by Henry Baker, F.B..S., 

 who had not been able to detect, the aperture ; but 

 on further examination, made on a large foreign 

 spider from the island of Nevis, he detected the 

 orifice, and " showed the same to Dr. Mead, who 

 was much pleased with the discovery." 



Dr. Mead, in his "Mechanical Account of 

 Poisons," 3rd edit., p. 88, says that he was " inclin- 

 able to believe that Mr. Leeuwenhoek had been 

 mistaken; and that the fangs were capable of in- 

 flicting a wound only, into which a poisonous liquor 

 was instilled afterwards by a short white proboscis 

 thrust out of the spider's mouth." 



ifc^fe 



Fig. 2(3. Ovipositor of Spider. 



To test the poisoning power of the spider, he 

 tells us that he " took a small frog, whose body was 

 about an inch and a half in length, which I put into 

 a glass tube together with a large spider, in order 

 to see the action of the two animals when brought 

 together, and I observed the spider pass over the 

 frog without hurting it, though with its fangs dis- 

 played as if to attack the frog. Upon this, I caused 

 the frosr to fall against the spider, who thereupon 

 struck his fangs into the frog's back, making two 

 wounds, one of which exhibited a red mark and 

 the other a purple spot. I then brought the 

 frog to the spider a second time, who there- 

 upon struck his fangs into one of the frog's 

 fore feet, whereby some \'e\v of the blood-vessels 

 were wounded; and having provoked the spider 

 a third time he struck both fangs into the frog's 

 nose, presently after which I took the spider out 

 of the glass. The frog thus wounded sat without 

 motion, and in about the space of half an hour it 

 stretched out its hind legs and expired." 



His experiment on another and a larger frog was 

 not successful, its superior size and strength no 

 doubt enabling it to resist, the effects of the venom. 



Leeuwenhoek now turns his attention to the 

 formation of the nest, and the deposition of the 

 eggs, of which he gives an interesting description. 



During his observations on the nidiflcation, lie 

 detected the method used by the spider for depo- 

 siting its ova. He says, " I was desirous to see a 

 spider laying its eggs, which at length I obtained a 

 sight of, and observed that they were not emitted from 

 the same part as usual in all other minute animals, 

 but from the fore part of its belly, not far from its 

 hind legs, and near the place I observed a kind of 

 little hooked organ, handsomely shaped, which J 

 had often before seen in the animal, and could not 

 imagine for what purpose it was designed ; but 

 now, I perceive that it extended over that part 

 whence the eggs issued, and I therefore conjec- 

 tured that its use was to deposit them in regular- 

 order within the web prepared to receive them. 

 This hook I then separated from the spider's body, 

 and, placing it before the microscope, I delivered it 

 to the limner that he might make a drawing of it as 

 it appeared to him." 



This drawing is given at fig. 26, "efgi k, 

 and therein between the letters I and k certain 

 folds or wrinkles appear, this organ being so formed 

 as to have a greater extent of motion action than 

 usual. The letters e f denote the part which was 

 joined to the spider's body." In order to discover 

 whether the eg^s could be hatched by artificial 

 warmth sooner than the usual time, which is in the 

 spring, he enclosed some on the 1st of January in a 

 glass tube, which he constantly carried about with 

 him. On the morning of the 17th he found twenty- 

 five young spiders, and in the evening of the same 

 day he counted above a hundred and fifty young 

 ones : on exposing them to the cold they became 

 motionless, but recovered on the application of 

 warmth ; on the 21st he was able to discern their 

 eyes, and on the 25th they began to open webs, in 

 the same manner as full-grown spiders. Leeuwen- 

 hoek was at a loss to understand how " these young 

 spiders could be supplied with nourishment, con- 

 sidering that the natural food of these creatures is 

 the substance of other insects ; but I now perceived 

 that they fed on the barren eggs which had been 

 left in the glass, and they afterwards devoured 

 one another till they were reduced to very few in- 

 number." 



That wonderful production, the web of the spider^ 

 was not likely to escape the notice and investigation 

 of Leeuwenhoek, and accordingly we find him 

 studying the spinnerets, of which a tolerably accu- 

 rate description and figure are given ; but he is most 

 struck with the amazing fineness of the threads, 

 and calculates their diameter : his standard of com- 

 parison is, as usual, a hair from his beard. He says, 

 " For this purpose I placed the thickest part of the 

 hair before the microscope, and, from the most 

 accurate judgment I could form, more than a hun- 

 dred such threads placed side by side could not 

 equal the diameter of one such hair. If then we 

 suppose such hair to be of a round form, it follows 



