258 



food (medium), air, moisture, and temperature. Their specific nature 

 has been determined by inoculation, according to the particular disease 

 to which they belong ; but when such a disease appears in the farm- 

 yard, or in the sheep-fold, there seems to be something else wanting 

 besides the conditions formulated in the laboratory. It has been 

 observed that some of these specific germs, like the germ of wheat 

 or of other grain, retain their vitality for a considerable time in a dry 

 condition, and that they are ever present with us in air, water, and 

 food. Now, if they are so ready to establish their action when 

 cultivated in the laboratory, all conditions being suitable, how does it 

 happen, that the various specific diseases these germs are said to 

 produce, are not ever present, and that all animal life has not been 

 destroyed ? Probably it is because, like seeds of higher organisms of 

 every kind, the surroundings must be replete and complete with every 

 necessary condition favourable to their germination and development ; 

 or, it may be essential that through some peculiarit}^ in the atmosphere, 

 locality, food, or other influences, acting either collectively or separately, 

 the body of the patient must first be brought into such a condition that 

 the particular germ specific to the malady, which has been lying latent, 

 finds the circumstances suitable for germination and growth. 



613. Symptoms. — Tetanus m a mild form is not readily detected, 

 but in its acute stages the symptoms are more prominent. The first 

 to be noticed are that : If the animal is made to walk, it moves stiffly, 

 and with a wooden gait. The head is extended forward, nose pointed 

 out, ears pricked out in front, there is straddling of the hind legs, the 

 hocks of which are turned out, and the tail is raised and shaking. If 

 the animal is in the stall, the hind legs are placed backwards, wide 

 apart, with the points of the hocks turned out, the tail elevated and 

 quivering, the head pulled up, and the eye very watchful ; whilst the 

 slightest noise seems to aggravate the symptoms. On approaching 

 the head, the animal recedes and drags the fore feet backwards, raising 

 the head higher ; the eye-ball is drawn back into the socket, and the 

 haw {memhrana nictitans) is stretched across the front of the eye, giving 

 it the peculiar appearance of a squint. The latter is looked upon as a 

 confirming symptom, yet the jaws may still be slightl}^ movable. But, 



