520 Dynamic Theory. 



mother, is often largely stimulated by the anticipation of suckling the 

 infant, or even thinking about it. The secretion of milk during preg-. 

 nancy, appears to be due to nervous stimulus S} r mpathetic with uterine 

 activity ; an association dating back to the earliest types of mammal 

 life, and even beyond. The mental state of the mother has an effect on 

 the quality as well as the quantity of the milk. .It is affected by a 

 fretful temper, by fits of anger, by grief, by anxiety of mind, by fear, 

 by terror, and by excessive indulgence of the passions and appetites. 

 Examples are given in which infants have been fatally poisoned by milk 

 which has been changed in the mother's breasts by her violent emotion 

 *or mental excitement. A case is given of a puppy which was seized 

 with epileptic convulsions on sucking its mother after she had been in 

 a fit of rage. ( Carpenter. ) 



Other secretions are equally subject to nervous stimulus effected 

 through mental action. Experiments upon dogs and pigs, show that 

 after they have been kept fasting awhile, a sight of food, which they 

 are not allowed to eat, provokes a flow of gastric juice into the stomach. 

 It is familiar to all, that the flow of saliva, the action of the lower in- 

 testines, the secretion of the kidneys, sexual secretions, tears, &c. , are 

 influenced by mental states. These facts are based on the nervous con- 

 nection between the secreting glands and the general nervous centers 

 brain and spinal cord. 



The sweat glands are subject to tttfe influence of the nerves, like the 

 salivary glands. It has been observed, that in amputated limbs, if the 

 distal ends of the nerves be irritated, a copious exudation of sweat may 

 occur. The sudoriparous, or sweat glands, have their nervous connec- 

 tion with the spinal cord corresponding with the nerves of general, sen- 

 sory and motor innervation. They are reflex, and can be operated when 

 the spinal cord is severed from the brain ; and they are also controlled 

 by mental states. The number of these minute glands is estimated at 

 two and a half millions, giving a secretory surface of nearly 1080 

 square meters. 



( A number of facts relating to the glands concerned in digestion, 

 have been mentioned in Chap. 28.) 



In general, glands are stimulated to action by the direct contact and 

 pressure of the substances they operate with, or reflexly through nerv- 

 ous stimulation coming from other organs with which they are in work- 

 ing relationship. The development in animals of both muscles and 

 glands, has been imitated, to a greater or less extent, by corresponding 

 parts in a few of the plants. Or, perhaps it would be more accurate to 

 say that the functions of muscles and glands, and even nerves, are per- 

 formed in certain plants by the cells of plants without any very distinct 

 specialization of the tissues. Most of the facts in this chapter, relating 



