44 CAUSES, SYMPTOMS AND TREATMENT OK 



tation set up by the flies, will make them be one swollen mass, from 

 both congestion and irritation. The flies present much the same 

 appearance as the house flies, but differ from them in having a sharp 

 proboscis. 



Remedies. — It is good practice to recommend cattle to be kept in 

 during the day and allowed to run out at night. Equal parts of oil of 

 tar, benzoin and linseed oil, carbolic acid lotion, are very nice in such 

 cases. 



Warbles in Cattle. — Having them in a horse is a mistake. This 

 is produced by a fly, which deposits an egg through the skin. The 

 puncture irritates to some extent ; this egg hatches, grows to a certain 

 extent, and produces an elevation called grub in the skin. They are 

 more likely to attack an animal of thin skin. Fine-bred cattle are 

 more liable to this than the opposite. The animal rubs and scratches 

 himself; after a time the grub comes out, or you may cut it out, or 

 puncture with a hot wire ; but it is better to use a lancet and take 

 it out. 



NERVOUS SYSTEM. 



The nervous system consists of a central portion, the cerebro- 

 spinal axis, emanating from which there are a number of white 

 glistening cords, called nerves. The centre or axis is divided into 

 two portions, one large and expanded, called encephalon, or brain. 

 The other is elongated in form, and is known as the spine or spinal 

 cord. There are nerves leaving this system, and are distributed to 

 those parts of the body under control of the will ; these are called 

 nerves of animal life ; they go to the muscles. There are two chains 

 of nervous ganglia, which extend along the vertebral column. The 

 nerves emanating from these are called nerves of organic life, and are 

 distributed to the viscera, heart, glands, and blood vessels. Some 

 parts are under the control of both these nerves. In the formation of 

 nerves we have two elementary structures : nerve cells and nerve 

 fibres ; the white and the gray matter. Ganglionic corpuscles are 

 found in the nerve centres, and in the extreme end organs of some of 

 the nerves they are capable of generating nerve force. They convey 

 impressions to and from the brain. The coverings of the brain and 

 cerebro-spinal cord are the dura-mater or outer, arachnoid or middle, 

 and pia-mater or the inner. The processes given off in the brain are 

 falx cerebri, tentorium cerebelli. The central covering, the arachnoid, 

 belongs to the serious class of membranes, and like all such mem- 

 branes, presents two coverings, the parietal and visceral. The pia- 

 mater is formed of minute blood vessels, held together by areolar 

 tissue. The dura-mater is attached to the cranial cavity, but is not so 

 attached in the spine. The brain proper is divided into four parts : 

 the cerebrum, cerebellum, pons varoli, and medulla oblongate. The 

 cerebrum is divided into two hemispheres by a longitudinal fissure, in 

 which the falx cerebri is lodged. The medulla oblongata is a con- 

 tinuation of the brain. The nerves which pass from the brain are 

 cranial nerves. There are twelve or nine pairs ; we generally take it 

 at twelve. They are : 



First, Olfactory, or nerve of the special sense of smell. 



Second, Optic, or nerve of the special sense of sight, which presents 

 no sensibility. These fibres start in two roots. Some pass from the 

 right side to the left bulb, and vice versa ; and some pass straight on 

 to the eye of the same side ; and some cross from one side to the other, 

 and do not go to the eye. 



