Sex Ratio of an Aranead 43 1 



by larger insects. The spiders were given equal amounts of food, 

 and from the beginning of the experiment until August 8 all were 

 richly fed, and daily except in the colder portion of the spring 

 when food was hard to obtain, so that each of them averaged 

 probably five or six blue bottle flies a day, quite the equivalent 

 of the amount in a state of nature. Between August 8 and 29 

 they received only two meals, for I was absent; and in September 

 they received only three good meals. Up through the first week 

 in August, which marked the close of reproduction with most of 

 them, these spiders were kept under natural conditions of hght, 

 temperature and amount of food. The healthy and active con- 

 dition of the captives until the middle of August, and the large 

 number of cocoons they produced, evidenced the favorable circum- 

 stances under which they were maintained. 



Each spider received a separate number, and each cocoon the 

 number of the mother together with the cocoon letter; thus the 

 first cocoon of spider 2000 was 2000A, the second, 2000B, and so 

 on. No cocoon was removed from a cage until several hours after 

 its construction, for when just made the danger of injury to the 

 eggs is greatest; each was lifted out as gently as possible with a 

 pair of forceps, placed in a bottle covered with perforated paper 

 and kept there until the young emerged; these wxre preserved in 

 80 per cent alcohol within twenty-four hours of hatching. It is 

 necessary to kill the spiderlings before their first postnatal moult, 

 else they commence to attack each other. This isolation of the 

 cocoons is the only method for preventing the young from dis- 

 persing and so becoming lost at the time of hatching. 



Three series of females were kept: (i) twelve individuals whose 

 young were allowed to hatch for the computation of the sex ratio; 

 (2) five individuals whose eggs were preserved twenty-four hours 

 after oviposition to test possible voluminal difi^erences; and (3) 

 two individuals kept to test parthenogenesis. More than this 

 number I could not keep well fed. No deaths occurred until 

 August 29, and the nine deaths from then on were probably due to 

 insufficient feeding commencing with the second week of August. 



