SECRETARY'S REPORT. 67 



any special excellence depending on form, or temperament, or ner- 

 vous energy. 



Not only should care be taken to avoid structural defects, but 

 especially to secure freedom from liereditai-y diseases, as both de- 

 fects and diseases appear to be more easily transmissible than 

 desirable qualities. There is often no obvious peculiarity of struct- 

 ure or appearance indicating the possession of diseases or defects 

 which are transmissible, and so special care and continued acquain- 

 tance is necessary in order to be assured of their absence in breed- 

 ing animals ; but such a tendency although invisible or inappreci- 

 able to cursory observation, must still, judging from its effects, 

 have as real and certain an existence, as any peculiarity of form or 

 color. 



Every one who believes that a disease may be hereditary at all, 

 must admit*that certain individuals possess certain tendencies 

 which render them especially liable to certain diseases, as consump- 

 tion or scrofula ; yet it is not easy to say precisely in what this 

 predisposition consists. It seems probable, however, that it may 

 be due either to some want of harmony between different organs, 

 some faulty formation or combination of parts, or to some peculiar 

 physical or chemical condition of the blood or tissues ; and that this 

 altered state, constituting the inherent congenital tendency to the 

 disease, is duly transmitted from parent to offspring like any other 

 quality more readily apparent to observation. Hereditary diseases 

 exhibit certain eminently characteristic phenomena, which a late 

 writer* enumerates as follows : 



1. "They are transmitted by the male as well as by the female 

 parent, and are doubly severe in the offspring of parents both of 

 which are affected by them. 



2. They develop themselves not only in the immediate progeny 

 of one affected by them, but also in many subsequent generations. 



3. They do not, however, always appear in each generation in 

 the same form ; one disease is sometimes substituted for another, 

 analagous to it, and this again after some generations becomes 

 changed into that'- to which the breed was originally liable — 

 as phthisis (consumption) and dysentery. Thus, a stock of cattle 

 previously subject to phthisis, sometimes become affected for sev- 

 eral generations with dysentery to the exclusion of phthisis, but 

 by and by, dysentery disappears to give place to phthisis. 



*Finlay Dun, Member Royal College of Veterinary Svu-geons, in Journal of . tha 

 Royal Agricultural Society. 



