18 DEPARTMENT OF GAME AND FISHERIES No. 9 



to create new kinds of living things; heredity preserves them. All progress in 

 breeding is based on the law of variation. No two animals are exactly alike; 

 a close examination will always re^•eal that they differ to some degree. By 

 making good use of these differences the breeder can turn them to his own 

 advantage. It is this variation in the individual that enables us to 

 select parents possessing the characteristics we desire to obtain in 

 the offspring. This method is termed selection and is one of the safest for 

 gradually raising the standard of the ranch. It is a very poor policy to mate 

 a good animal to a poor one, with the idea of getting fair, average stock. The 

 outstanding males and females should be mated together and from the results 

 of such matings, careful selection, accompanied by line and in-breeding, can 

 then be attempted. 



A great deal of confusion exists among breeders regarding these two terms, 

 for the very good reason that no two writers on the subject appear to make 

 use of the same definitions. Generally speaking two methods may be employed: 

 one where in-breeding is confined to the mating of some degree of cousins; the 

 other where the relationship becomes closer, such as sire to daughter, dame 

 to son and brother to sister. It is immaterial from a practical standpoint 

 what either system is called; the main point for the breeder to grasp is that 

 it is not advisable to breed brothers and sisters or animals that are too closely 

 related. Experienced breeders, who are first class judges of their animals and 

 know what true value to place upon a pedigree, may practise close-in breeding 

 on occasions and secure excellent results in some cases, but it is not to be recom- 

 mended for the average rancher. Close in-breeding can only meet with success 

 if the owner has the ability to determine -whether or not the desirable qualities 

 expected will offset any defects that will tend to become concentrated in the 

 offspring. 



The safer method is to mate no closer relationship than first cousins. For 

 example, there may be two outstanding females on the ranch, full sisters to each 

 other and mated with two males of good quality. The pups from the mating 

 are first cousins and provided they show desirable qualities, they can be inte.- 

 mated with each other. By mating these cousins we are concentrating what 

 appears to be high-class breeding stock. From this generation we can carry 

 on indefinitely the mating of animals not closer than cousins, and yet having 

 common ancestry behind them of known worth. 



This method of breeding, combined with the culling of all low grade animals 

 which inevitably appear from time to time in the best of stock, will result in a 

 steady improvement in ranches where it is practised. 



These ideas are not only applicable for the improvement in pelt value, but 

 can be used to eliminate undesirable characteristics as small producers, pup 

 carrying, indifferent mothers, cannibalism, and noisy nervous foxes, etc. Such 

 traits can be intensified or eliminated to a great extent by selection and wise 

 breeding. 



Congestion of the Lungs in Mink 



This condition became very prevalent among mink during the extreme 

 heat waves experienced in the months of July and August. Mink carcasses 

 were received for examination from all parts of the Province of Ontario and the 

 Maritimes, showing a pronounced congestion of the lungs due to heat stroke 

 and heat prostration. 



Symptoms. — The majority of these cases were females that had been left 

 with their young and in some cases were still nursing. Some of them were 



