September 11, 1885.] 



SCIENCE, 



227 



Microscopic anatomy should show : 1°. Tlie nature 

 and relations of the structural elements which com- 

 bine to form any organ or tissue. 2°. The blood- 



supply. 



The lymph-supply. 4°. The nerve-sup- 



ply, and relation of the nerves to the structural 

 elements. 5°. The development of the structural 

 elements, and their combination to form the various 

 tissues. The structure of no tissue or part is known 

 in all this detail. This is both encouraging and dis- 

 couraging; for, while we see many problems unsolved, 

 we know that they are problems which have eluded 

 the grasp of the greatest anatomists of the world. 



It is often said that a certain tissue must perform 

 a given function on account of its structure ; but we 

 know that a moner or an amoeba performs all the life 

 functions observed in the higher animals, and hence 

 it seems hopeless to tell by structure alone what the 

 function of individual cells composing one of the 

 higher animals must be. Claude Bernard has said 

 that structure is the key to the grosser and merely 

 mechanical functions alone; and this is fully justified 

 by the facts, that, before his work, the liver was 

 thought to simply produce bile, and the pancreas to 

 secrete saliva; yet the physiologist Bernard found the 

 liver a manufactory of sugar, and the pancreas pro- 

 ducing a juice with the powers of all the digestive 

 ferments combined with the power of emulsifying fat. 

 While, therefore, the most intimate structural knowl- 

 edge gives no hint of the function of a tissue, it is of 

 great value when the function is known in determin- 

 ing the significance of the structural relations. 



Knowing the special differentiations accompanying 

 a function, it is usually safe to assume that a similar 

 structure will possess similar properties, and perform 

 nearly the same function, no matter where found. 

 Structural knowledge is also of great value to the 

 morphologist, helping him to recognize and homolo- 

 gize the organs of different animals. Finally, without 

 the knowledge of structure added to the knowledge of 

 physiology, the splendid achievements of modern sur- 

 gery would be impossible. While our structural 

 knowledge is already great and valuable, our insight 

 into the relations of structure to function is still very 

 slight. 



While specialization of function and differentiation 

 of structure are concomitant, no one as yet can state 

 the finer structural relations which accompany ex- 

 treme specialization of function. It is not difficult 

 to detect a nerve-fibre; but, from appearance, no one 

 can yet say whether its function is associated with mo- 

 tion, sensation, or secretion: between these functions 

 the gulf remains impassable. 



Let me now call attention to the structure of an 

 organ in the pharynx of the soft-shelled turtles, and 

 briefly state my reasons for claiming that the mucous 

 membrane of the pharynx is a respiratory organ. 

 These turtles remain voluntarily from two to ten hours 

 under water; and, while under, fill the pharynx with 

 water, and expel it about sixteen times per minute: 

 water so used has lost part of its free oxygen, and 

 gained much carbon dioxide. 



The pharyngeal mucosa is densely covered with 

 minute cylindrical compound, or filamentous papillae, 



having the appearance of the villous coat of the in- 

 testinal mucosa. This membrane begins opposite the 

 tongue's base, and extends to about opposite the third 

 cervical vertebra, where it passes into the oesophageal 

 mucosa, the beginning of which is surrounded by a 

 sphincter, thus marking off the respiratory chamber. 

 The epithelium of the mouth, pharynx and oesopha- 

 gus consists of nonciliated nucleated cells, is many 

 layered and stratified in the mouth, but gradually 

 becomes columnar in the pharynx. The columnar 

 cells are interspersed with small cells wedged into 

 the spaces between their inner ends. Both kinds of 

 cells send processes from their inner ends to help 

 form the strong basement membrane. Sometimes 

 the small cells are connected with the stellate cells 

 of the deeper tissue by long processes. Beaker cells 

 are found in the pharynx and oesophagus, but not 

 in the strictly respiratory part. The blood-supply is 

 copious, consisting of a capillary net work. A plexus 

 of non-nucleated nerves gives off branches to the papil- 

 lae, and probably terminate in the taste-buds (neuro- 

 epithelia) found there. 



Such is in brief the structure of this membrane. 

 What is the special significance of this structure? 

 Does it agree with other respiratory membranes ? 

 In the gill of a fish the blood-supply is abundant, as 

 here; but the epithelium is tessellated, not columnar. 

 In the external gills of the tadpole and newt, the 

 structure is much the same, except that a columnar 

 ciliated epithelium intervenes between blood-supply 

 and the water. In the inner gill of the tadpole and 

 external of Necturus a pavement epithelium is pres- 

 ent. If compared with the lung membranes of air- 

 breathers, there is a general agreement of structural 

 facts ; but the structure of each of these membranes 

 stands out clearly from all the rest, that of the turtle 

 resembling none so much as it does the villous mem- 

 brane of the small intestine of a mammal. Yet the 

 principal function of each of these membranes is 

 the passing into the blood of oxygen, and the passing- 

 out from the blood of carbon dioxide. That these 

 membranes vary widely as regards structure, while 

 possessing identical functions, is but one more demon-" 

 stration of the fact that, if we would have the whole 

 truth, the study of structure and function must go 

 hand in hand. 



PROCEEDINGS OF THE SECTION OF 

 HISTOLOGY AND MICROSCOPY. 



We have to record the cessation of sec- 

 tion Gr, histology and microscop.y, of the 

 American association. This anomalous sec- 

 tion, finding its end near, proceeded with 

 dignit}^ to request the association to kill it : 

 the request has been granted, and we are con- 

 sequentty forced to write an obituarj' of an ex- 

 istence which we have long disapproved. Not 

 that we are in anyway opposed to microscopy, 

 the most delightful of what-not sciences, but 

 because microscopy had to be dignified by rob- 



