XIV POISON FERTILITY " 365 



species regarded as especially venomous must be mentioned 

 Phidip2^us morsitans, one of the larger of the Attidae. 



It is exceedingly likely that the bite of the large tropical 

 Avicvilariidae is really formidable. They appear, however, more 

 anxious to escape than to show fight, and we possess little reliable 

 information with regard to them. Doleschall shut up small 

 birds with two West Indian species, and death followed their 

 bite almost immediately. Ten days' starvation appeared to 

 weaken the venom, for a bird bitten by a spider fasting for that 

 period recovered after an indisposition of six hours. 



Most Arachnologists have recorded experiments with regard to 

 the venom of the commoner European species, with equally con- 

 flicting results. Blackwall came to the conclusion that loss of 

 blood, and not poison, caused the death of spider-bitten insects. 

 He could not himself distinguish a spider bite from the prick of 

 a needle inflicted upon his hand at the same time. Bees, wasps, 

 and grasshoppers survived the bite about as long as other insects 

 of the same species outlived a needle-prick in the same part of 

 the body. Walckenaer's experience was of the same nature. 

 Bertkau, however, when bitten in the hand, felt clear indications 

 of an irritant poison in the wound. The hairs of some of the 

 large hairy species of the Aviculariidae possess poisonous 

 properties. They are readily parted with, and when the animal 

 is touched by the hand considerable irritation is set up. 



Fertility of Spiders. — Spiders vary greatly in the average 

 number of eggs laid by different species, and within the limits of 

 each species there is a very considerable variation in fertility. 

 As a rule it appears that the large and vigorous spiders are more 

 prolific than the smaller and weaker members of the order. 

 Were all the facts before us, however, we should no doubt find 

 that the number of eggs laid bore a direct proportion, not to the 

 size of the species, but to the dangers to which the young of 

 that species are exposed. Where the total numerical strength of 

 a species is fairly stationary, such a proportion must of course 

 exist. Some species, no doubt, are tending to become extinct, 

 while others are increasing in numerical importance. As a 

 general rule, however, it is safe to infer that, if a species is 

 especially prolific, special dangers attend the rearing of the young. 

 The largest of North American Epeirids, Argiope cophinaria} 

 ^ M'Cook, American Sjiiders and tlieir Spinning JFork, ii., 1890, p. 188. 



