COCOONING AND HATCHING OF AN ARANEAD. / 



17 days. The majority, accordingly, hatched at intervals of from 

 14 to 1 6 days. Different generations of cocoons do not have 

 different rates of hatching. Cocoons made on the same day 

 need not hatch at the same time; thus of 8 cocoons made on Au- 

 gust 20, 3 hatched in 1 1 days, 2 in 13 days, 2 in 14 days, i in 

 1 6 days ; and of 1 1 cocoons made on the morning of Au- 

 gust 26, 9 hatched in 14 days, and 2 in 16 days. All these co- 

 coons were removed from the web, placed in separate glass vials, 

 and kept together under the same conditions of light, tempera- 

 ture and moisture. The differences in the rate of hatching are 

 probably due to the difficulties experienced by the young in 

 emerging, for where the cocoon is thinnest the hatching is earliest. 

 Most of the spiderlings emerge in the early morning, but they 

 may come out in the late morning and the afternoon. Each 

 of the few most vigorous spiderlings makes a small circular 

 aperture through the wall of the cocoon, and through these 

 few openings all the rest find their way. The young are at first 

 decidedly positively heliotropic, and it is the light shining into 

 the first made exits that probably guides the less precocious 

 individuals out of the cocoon. The weakest may not emerge 

 until several hours or even days after the most vigorous. In 

 this species, unlike the lycosids, I have found no evidence that 

 the mother aids the young to hatch ; for I removed from the 

 webs a number of cocoons immediately after their completion, 

 thus precluding any opening of the cocoon by the mother, yet 

 all of the young made their way out. The mother exhibits 

 some degree of bravery in guarding the cocoon, especially when 

 the latter is newly formed, though never to the extent of allow- 

 ing herself to be injured, and if she is roughly handled she invari- 

 ably drops from the web. 



8. Protective Value of tlie Cocoon. I removed eggs, at various 

 intervals after oviposition, from cocoons and placed them in flat 

 glass dishes in the ordinary diffuse light of the laboratory ; in all 

 these cases normal spiderlings resulted. Therefore the presence 

 of a cocoon is not necessary to normal development and, further, 

 its value is probably not to exclude the light. One batch of 

 eggs was opened onto a dish of water, where they floated ; after 

 a number of days they become covered by a mould that killed 



