598 



SCIENCE 



[N. S. Vol. XXIX. No. 745 



If amitapsis should prove to be associated with 

 self-fertilization it would help to explain why self- 

 fertilized plants produce highly uniform progeny, 

 aa in vegetative propagation, whereas the progeny 

 of normally cross-fertilized plants have notable 

 individual diversity. Germ-cells arising through 

 amitapsis could be viewed as vegetative products, 

 rather than as fully sexual products of conjuga- 

 tion. It is easy to understand that the union of 

 amitaptic germ-cells might merely reproduce the 

 parental characters. Thus amitapsis may account 

 for the uniformity of self-fertilized types, as well 

 as for their liability to mutative derangements 

 of characters. 



The regular program consisted of the following 

 communications : 



The Blue Foxes of the Pribilof Islands: James 



Judge. 



The blue foxes of the Pribilof Islands are pre- 

 sumed to have come from the mainland of Alaska 

 on the ice with which Bering Sea is filled during 

 winter. The caves and subterranean passages left 

 by the volcanic upheaval furnish the foxes with 

 homes. 



In summer the bird life furnishes an abundance 

 of the choicest fox food. When the birds depart 

 in the fall fox food consists of drift from the 

 beach and the bodies of seals or sea lions which 

 have either been killed, or died the preceding 

 summer. This was ample until 1890, when the 

 lessened seal and sea lion catches reduced the 

 winter food supply and many of the animals died 

 of starvation. The dead were eaten by the sur- 

 vivors, and the death rate in consequence was not 

 noticed. 



Since 1896 all seal meat not used by the natives 

 on St. George Island has been salted and the fol- 

 lowing winter freshened and fed to the foxes. The 

 seal meat, being insufficient in quantity, has been 

 supplemented by dried or salt fish. 



Coincident with the regular feeding begun in 

 1897, the old methods of trapping were abandoned. 

 These consisted of death traps, so called, and 

 steel traps, and a method of taking foxes from 

 their warrens. The method of trapping now in 

 vogue consists of capturing the animals in a large 

 cage, in which the food intended for them is 

 placed. Upon capture, the animals are subjected 

 to a rigid examination and all undesirable ones 

 are killed forthwith. Males left for breeding pur- 

 poses must weigh at least 10 pounds and females 

 at least 7i pounds, and be either young or in the 

 prime of life. In taking the live weights a strap 



is looped around the tail and the beast suspended 

 from a spring balance attached to the ceiling of 

 the building. The age is determined by an exam- 

 ination of the teeth. This is done by inserting a 

 soft gag in the mouth and inspecting the teeth 

 at close range. Those dismissed as breeders are 

 branded by cutting a ring in the fur of the tail, 

 males being branded near the end, females near 

 the base. The men handling the foxes use heavy 

 leather mittens. 



On post-mortem examination of the animals 

 killed in trapping the stomachs are found to carry 

 in addition to the bait taken in the trap, grass, 

 feathers, wild parsnip, fish bones, bird or seal 

 bones, dirt or sand, and occasionally tunicates, 

 sea eggs and fox fur. The intestines vary between 

 six and ten feet in length, and were found to carry 

 grass, feathers, wild parsnip, dirt, gravel, bones 

 and sometimes tunicates and fox fur. 



The bulk of males weighed between 8J and 13i 

 pounds. That of females between 6 and 11 J 

 pounds. Male skins when ready for market meas- 

 ure on an average 30 inches in length, 11 in 

 breadth; the females are about one inch shorter 

 and an inch narrower. The tails of both sexes 

 are about the same length, viz., 15 inches. As a 

 rule the fur of the female is inferior to that of 

 the male, and among the males the best fur is 

 found on the two- and three-year olds. 



The breeding season is confined to March and 

 the first half of April, and the young are born in 

 litters of from five to twelve, in May and early 

 June. Birth is given on the surface of the ground, 

 but shortly afterwards the mother transfers the 

 young to some place under ground, from which 

 they do not emerge until several weeks old. While 

 the birth rate is large, the infant mortality is 

 very great, as only about two per female, on an 

 average, reach maturity. They are born blind and 

 weigh about 2i ounces each. The eyes open on 

 the fifteenth day, by which time the head and the 

 tail take on a fox-like appearance. The teeth 

 come through at or shortly after this time. 



Occasionally one white fox is found in a litter 

 of blue. Since 1897 a continuous effort has been 

 made to exterminate white foxes, and results indi- 

 cate that in time this will be accomplished, or 

 at least that the white strain will be reduced to 

 a minimum. 



Evidence of diseases is scanty. Two cases of 

 tuberculosis, one of uremic poisoning and thirteen 

 cases of mange have been discovered. From the 

 evidence at hand the males seem better able to 



