22 A CKITICAL PEKIOD IN THE 



established, with the result that it is sooner or later discharged. 

 Hence the necessity of having vigorous germinal cells to start 

 with — in other words, of the breeding stock being in a healthy 

 and vigorous condition ; for whether it is or is not possible to 

 transmit acquired characters, it is certainly possible, by means of 

 unsuitable surroundings and injudicious feeding, to diminish the 

 vitality of both the eggs and sperms. 



With regard to the immediate surroundings of the embryo, 

 probably the conditions are oftenest rendered unsuitable for the 

 development of the embryo by an unhealthy state of the uterine 

 mucous membrane. The uterine secretions may be acid instead 

 of alkaline (they are said to be acid in mares that have fre- 

 quently broken service ; acid secretions destroy the sperms as 

 they pass upwards through the uterus), excessive or the opposite. 

 They may, on the one hand, be unsuitable for the due nourish- 

 ment of the embryo, or they may prevent it being properly fixed. 

 At a later period, by accumulating between the basis of the villi, 

 the secretions may actually dislodge them from their pits. But 

 even should the mucous lining of the uterus be normal, neither 

 too congested nor too anaemic, nor yet too irritable, the muscular 

 fibres which enter so abundantly into the uterine wall may be 

 out of order, or the nerves supplying them in a state of unrest. 

 The fibres in the neck and body of the uterus may be relaxed or 

 wanting in tone, or the fibres of the horns, or it may be of the 

 whole organ, may be subject to frequent spasmodic contrac- 

 tions. Whether such contractions result from local irritation or 

 general nervous excitement, if excessive and long continued, the 

 chances of the embryo being long retained will be extremely 

 small. 



The question now arises, can anything be done to prevent 

 mares breaking service ? In dealing with the horse, the fact 

 must never be lost sight of that he is an extremely high-strung 

 animal, liable in a panic to completely lose the little self-control 

 he has inherited from his wolf -worried ancestors. This nervousness, 

 which was his salvation when in a wild state, has in some respects 

 been increased rather than diminished by the unnatural life it is 

 now his lot to lead. The horse has strong likes and dislikes, and 

 frets often when separated from his companions. Tins being the 

 case, it will be easily understood that sudden changes — changes 



