VOL. XXII.] PHILOSOPHICAL TRANSACTIONS. 597 



produced by one, and in how short a time, we cannot conceive whence, or how 

 they get their food, especially as the old ones, as far as I could see, feed upon 

 nothing but animals. 



January 22d, I observed that the legs of many of the spiders, which before 

 had been clear and transparent, now assumed a dark colour, and afterwards be- 

 gan to be covered with hair, whereas I could perceive none a little before. 



On the 23d, their legs grew darker, as also the hinder part of their bodies, 

 whence their web proceeds, and that also began to be covered with hairs ; then 

 I observed likewise a great many particles of a moist or watery matter hanging 

 on the sides of the glass, which moisture I had not before taken notice of; but 

 now there was so much of it, that the barren eggs, which before rolled freely 

 about the glass, were glued to it by this viscous matter, which so much 

 abounded, that the young spiders could hardly pass through it. I observed also 

 that they had cast their very thin skins, and began to be much nimbler in their 

 motions. 



The 25th I saw them spin a thread, and manage it with their hinder-feet as 

 well as the old ones ; I observed also that they had eat up the barren eggs, and 

 the others wherein I supposed the young ones to be dead, which were about 

 50 in number : for a few days after there remained nothing but the bare shells. 



I have compared the threads of a full-grown spider with one of the hairs of 

 my beard ; the thickest part of which placed before the microscope, and accord- 

 ing to the nicest observation, I judged that above 100 of those threads laid 

 together, did not equal the diameter of one hair ; now supposing this hair to 

 be round, then 10 of the fine threads of a spider's web are not thicker than 

 one single hair. Now if we add to this, as it is most certainly true, that 400 

 young spiders, when they first begin to spin, are not, one with another, larger 

 than one full-grown spider, and that each of those young ones is provided 

 with all the working instruments of the old one, it would follow that the 

 smallest thread of such a young spider is 400 times smaller than that of a large 

 one, and if so, then 4000000 threads of a young spider are not so large as a 

 hair ; but then again, if we consider of how many parts one of those smallest 

 threads consist, we must stand astonished at the thought. I observed that half 

 the young spiders were smaller in the hinder part of their bodies than the rest, 

 which last I supposed to be males. Also that most of these young spiders had 

 bored into- the web, and in a manner lodged themselves in it, which made me 

 suspect that for want of other meat they had fed on the web, and the rather 

 because some of them were grown pretty much. 



January,30th, most of them were employed in weaving their web, so that the 

 glass swarmed with them. 



