262 DESIGN IN NATURE 



connecting fibres are self-acting, and require nothing outside of themselves but their natural objectives to evoke 

 their peculiar powers. Their operations are, in no sense, automatic or mechanical. They do not require to be jogged 

 into activity by any form of extraneous stimulation. On the contrary, the operations of the nerve centres are due 

 to original endowment. Thev form part of the original animal. This is proved by the new-born infant sucking 

 as soon as the teat of the mother is placed in its mouth. The reflex acts are inaugurated at birth and continued 

 throughout the entire adult state. A most intimate connection obtains between the gangUa or nerve centres of the 

 cerebro-spinal and sympathetic systems of nerves ; their operations in many instances being co-extensive. ihey 

 form part of one great nervous system, and, in the healthy animal, act together or in conjunction. It is only in 

 the diseased or mutilated animal that they may be said to act separately. 



Much confusion unfortunately exists as to the true nature of reflex action. As explained, it is umversally 

 referred by physiologists of the present day to irritability in the animal, and to extraneous stimulation of its nerve 

 centres. This, as I have pointed out, does not afford a satisfactory explanation. Reflex action is said to preside more 

 particularly over and produce the involuntary movements of the body, such as the circulation, the respiration, 

 ahmentation, the vegetative functions, &c. The theory of irritability and artiflcial stimuh, as apphed to reflex 

 action, when carefully examined, is found to be misleading and untenable. 



I quote recognised examples of reflex action to prove this statement. 



1. Sneezing is said to be due to irritation of the Schneiderian membranes acting on certain nerves reflexly. 

 Sneezing, I would observe, is an interrupted or non-continuous act. The irritation of the membranes referred 

 to could not through the instrumentality of a reflex act produce such a movement. 



2. Winking of the eyelids .—This is said to be due to the irritation of hght falUng on the sensory nerves of the 

 conjunctiva, which act reflexly. Winking, hke sneezing, is an interrupted rhythmic movement consisting of the 

 alternate closing and opening of the eyelids. The same irritation acting upon reflex nerve centres could not 

 possibly produce the closing and opening movements, which are diametrically opposite in character. 



3. Contraction of the iris of the eye is stated to be due to the stimulus of luminous rays of various kinds acting 

 on the optic nerve. In reply I have to observe that the hght is always present or constant, and it could not by 

 any nerve arrangement (reflex or otherwise) produce the occasional opening and closing movements referred to. 

 If the light as an irritant produced the opening of the iris, it could not also produce the closing of the iris ; these 

 movements in many cases following each other rapidly. 



4. Swallowing.— This, operation is said to be due to the irritation produced by the presence of a boluis of food 

 in the oesophagus. If this were so, it would result in the closing of the part of the oesophagus in front of the bolus, 

 which is the point first touched. As a matter of fact, the closing takes place behind the bolus — the part of the 

 oesophagus in front of the bolus spontaneously opening at the same time. It is quite evident that these opposite 

 movements cannot be due to the presence of the bolus or any form of reflex action caused by irritation and 

 stimulation. 



5. Opening and closing of sphincters. — In the stomach, the pyloric valve or sphincter is said to be opened by the 

 forcible contraction or closing of the body of the viscus ; the irritant which produces the closing of the stomach, 

 it is affirmed, being the food in conjunction with certain nerves (splanchnic and intestinal). In this connection 

 I may state that no power exerted by the contracting stomach could possibly force the narrow passage of the 

 sphincter. In reality, the sphincter opens or dilates spontaneously when the stomach closes or contracts. The 

 double movement (centripetal and centrifugal in character) is a co-ordinated rhythmic movement, and the one is 

 independent of the other. It is maintained by the mechanical school that the food (plus the nerve centres) is the 

 cause of the closing or contraction of the stomach and of the dilatation or opening of the sphincter. This explana- 

 tion is wholly unsatisfactory and inadequate. The movements of the stomach and its sphincter are exactly the 

 opposite of each other, and it is, on the face of it, incredible that the same food could produce diametrically opposite 

 movements, especially if those movements follow each other rapidly and are more or less rhythmic in character. 

 What is said of the stomach and its sphincter is equally true of the rectum and its sphincters, of the bladder and 

 its sphincter, the uterus and its sphincter, and the hollow viscera generally. 



G. When the theory of irritability and stimulation, plus reflex nerve action, is apphed to the heart of the 

 reptile, bird, and mammal, it is equally disappointing. If the heart of the mammal be taken as the example, it is 

 said that the interior of the several compartments of the heart is irritable, and that the blood and certain nerve 

 centres form the stimulus which causes the several chambers of the organ to open and close alternately with time- 

 regulated beat, which ceases not night nor day. The objections which I took to the explanations given of the 

 action of the hollow viscera and their sphincters apply with equal and, if possible, greater force to the explanation 

 given of the action of the heart. The mammalian heart consists of four compartments, and is bountifully supphed 

 with nerves and nerve ganglia. The accepted theory is that when the two auricles close or contract they 



