Herr N. Daniin on Parthenogenesis in Spiders. 27 



always already shrivelled and dry, since they were unfer- 

 tilized. Nineteen days afterwards (consequently on the 27th 

 of July), during which time, in the case of fertilized ova, the 

 young are wont to emerge, I opened the cocoon, and saw in 

 this instance, contrary to all expectation, developed young 

 ones. The egg-membranes had already burst. I counted 

 sixty-seven young spiders. 



Under the microscope the egg-membrane presented the 

 appearance of a delicate glassy substance; it was smooth and 

 destitute of a coating of hairs. The young had arrived at the 

 stage at which a distinct movement of the little blunt legs is 

 recognizable. The ceplialothorax was glistening white, tlie 

 legs were blackish, and the abdomen dark-coloured. To 

 discover the reason of these shades of hue I placed first one 

 of these young spiders entire, and afterwards various separated 

 portions of the body, beneath the microscope, when I saw the 

 coat of hair in process of origin beneath the integument; the 

 little hairs stood almost parallel one to another, and closer 

 together upon the legs than upon the abdomen ; the former 

 consequently appeared darker in colour than the latter. It is 

 not until the young spider has undergone yet another ecdysis 

 that it appears capable of leading an independent existence. 

 I removed these young ones : the old female remained in good 

 health and lively, and continued to feed and to spin. 



Two days later, that is on the 29th of July, I opened the 

 box in which I had placed them, and found that all the young 

 ones had emerged. Beside them now lay the second skin, 

 so that, as I have observed in the case of other spiders also, 

 they had moulted after a couple of days ; by this time they 

 were also recognizable as specimens of Filistata both in form 

 and colour. They ran about readily, and, after a few days, 

 were already able to lie in wait for their prey*. 



1 likewise examined these skins under the microscope, and 

 found that I was not deceived on the first occasion ; these 

 membranes had no hairs upon them, while tlie cuticle of the 

 young spiders is thickly clothed with hair, which could now 

 be seen standing up. 



These young iilistata are still living, and have already 

 successfully accomplished one ecdysis outside the cocoon. 



Are we not entitled to regard this case as a proof that 

 parthenogenesis occurs in Filistata testacea and, perhaps, in 

 other spiders also? There can here be no question of any 

 mistake. Filistata is very common in the Croatian littoral : 

 it lives in holes in old walls, and is recognizable by the star- 



* To lie in wait — because Filistata spins a peculiarly sticky web, to 

 wbich everything- adheres. 



