514 IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



The digestive tract of a ruminant is large and capacious and 

 before digestion can be normal bulky feeds must be present to 

 distend the digestive organs, stimulate peristalsis, separate the 

 particles of more concentrated feeds and so allow of their being 

 properly mixed with and acted on by the digestive fluids. Milk, 

 being highly digestible and free from fibrous material, is not a 

 "bulk}^" feed, though its nutrients are present in a rather large 

 volume of water, and so it can not, when fed alone, induce the 

 digestive system of older ruminants to function properly though 

 it is quite efficient with young ealves as in their case the rumen 

 is relatively smaller in comparison with the rest of the digestive 

 tract than it ultimately becomes. 



Where digestion is retarded or hindered, as would occur wheii 

 the digestive system became atonic due to the absence of rough 

 age, the materials not completely acted on by the digestive .juices 

 would remain in the alimentarj^ canal and undergo putrefactive 

 changes. The products of such putrefaction are toxic and when 

 absorbed from the alimentary canal can produce auto-intoxica- 

 tion with symptoms similar to those found with the experimental 

 animals in this case. 



Another fact worthy of note is that these calves were at times, 

 when averaging about 150 pounds, in live weight, consuming 

 over half as much salt per day as would a thousand-pound 

 animal. It has been found at this station that normally fed 

 calves of similar weight will consume about .01 pound salt per 

 day while the experimental animals consumed as much as .03 

 pound per day. 



This excessive salt consumption may have been an attempt to 

 correct digestive disturbances, or it may have been caused by 

 other physiological demands, or it may simply have been due to 

 the calves forming a pernicious habit. 



That sodium chloride can produce tetanic convulsions such 

 as were evident in the case of the experimental calves has been 

 shown on several occasions. Loeb^ demonstrated the contrac- 

 tions and final tetanus of muscles in contact with certain salt 

 solutions and he later-* showed that solutions of common salt could 

 cause rhythmical twdtehings and an increase in the irritability ot 

 muscles and nerves. This is due to an increase in the concentra- 

 tion of sodium ions and can be counteracted by the addition of 

 calcium salts. It has also been pointed out by MacCallum^ that 

 intravenous injections of solutions of sodium chloride increase 



