218 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



How long does the brood remain thus massed? This depends greatly 

 upon circumstances, particularly the velocity of the wind and 

 temperature of the air. A brisk wind and fair day tended to 

 scatter my experimental spiderlirigs very rapidly; indeed, during the after- 

 noon and night. This will best be illustrated by the following case. 



V. 



An interesting example of the habit of > young spiderlings immediately 

 after escape from the cocoon, was seen May 23d, 1887, in a ravine upon 

 the ground of Ogontz, a young ladies' school in the vicinity of 

 ^ 1 * Philadelphia. When observed, the little creatures were snugged 

 together in a ball underneath a large leaf of Indian turnip or 

 Jack-in-the-pulpit (Arisajma triphyllum). Two smaller individuals of the 

 same plant stood on either flank. The tall central plant served as a sort 

 of tent pole, and from the margins of the broad top leaves a delicate 

 silken tissue spread downward to the edges of the shorter Jacks mentioned. 

 There was thus formed a symmetrical pavilion, within which the spider- 

 lings were contained, and which presented all the appearance of having 

 been constructed intentionally. I am confident, however, that the deli- 

 cate canvas wall of this tiny tent was simply formed by the immensely 

 multiplied threadlets which the colony continually dragged after them as 

 they moved back and forth, up and down, in the preparatory stages of 

 settling themselves. 



When first observed, the whole colony was massed in a ball as large 

 as a walnut underneath one of the top leaves. The spiders were of a 

 yellowish brown color, and gave a pretty appearance as seen 

 through the silvery white of the silken wall against the green 

 background of their tent roof. When I tapped lightly upon 

 the top of the leaf beneath which they were snugged, the ball instantly 

 broke up, and a hundred or more of the little fellows dropped swiftly 

 downward. Every one dragged after it a silken attachment, which filled 

 the inside of the pavilion with perpendicular lines. Most of the number 

 returned in a little while to their position. Some remained hanging at 

 various distances; a few who had fallen quite to the bottom of the tent, 

 which was limited by the top leaves of the two flanking Jack-in-the- 

 pulpits, ran out from under the edge of the tent and extended their ex- 

 cursion for a little distance beyond. 



When I left the brood, Miss Skinner, the teacher of natural history in 

 Ogontz, kindly consented to keep it under observation, and I am indebted 

 to her for the following history prolonged through a period of ten days : 

 The colony was first observed on the morning of May 23d. The next 

 day was rainy and windy. On the 25th it was found that great rifts had 

 been made in the overhanging web or pavilion wall on the leeward side ; 



