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Curious problcme in tbe StruoQlc for Xifc. 



By Mrs. Alice Bodington. 



'"T^HE immunity of some animals from the evil effects of bacterial 

 X and other poisons fatal to others is one of the most obscure 

 problems in biology. Many interesting instances have been 

 given by Dr. Clifford Allbutt, in his address before the British 

 Medical Association at Glasgow. Many years ago, Darwin men- 

 tioned the curious fact that black pigs in Florida are unaffected by 

 feeding on blood-root, which has the property of giving a red 

 colouring to the bones ; whilst white pigs are fatally injured. 

 White pigs also suffer from eating buckwheat, on which black 

 pigs thrive. 



Pasteur relates that Cochin-China fowls resist chicken cholera, 

 and that the field-mouse resists the septicaemia, so fatal to 

 the house-mouse. Koch finds that the normal blood of the 

 latter forms crystals with difficulty, whereas that of the field- 

 mouse gives crystals readily. It is hardly to be supposed, 

 however, that these latter facts have anything to do with the 

 immunity of the field-mouse ; possibly, his wild habits have given 

 him a stronger constitution. The delicacy of white animals may 

 be the effect of higher or more artificial cultivation. It is well 

 known that new sorts of potatoes are at first disease-proof, but in 

 ten or twelve years these varieties, though apparently healthy, lose 

 their immunity, and new seedlings have to be raised. New 

 species of vines introduced into a district are proof at first against 

 the attacks of the phylloxera. This immunity of new species has 

 enabled the inhabitants of Madeira to make their island a vine- 

 growmg district again. AVhite-cocooned silkworms resist the 

 disease which destroys the yellow. Algerian sheep are not 

 subject to anthrax. Cattle and swine are very subject to pearl- 

 evil, while the goats which graze beside them escape. The dog is 

 almost insusceptible to glanders ; while the ass and the guinea- 

 pig, belonging to most widely difi"erent orders of animals, escape. 

 Leprosy is absolutely incommunicable to any animal except man. 

 Peptones, which prevent the coagulation of the blood in carni- 



JouRNAL OF Microscopy and Natural Science. o 



New Series. Vol. II. 1889. 



