98 GLANDS. 



mogastric and the great sympathetic. They ramify 

 in company with the bronchi and branches of the 

 pulmonary artery, and present, at intervals, minute 

 enlargements composed of nerve cells ; their mode of 

 termination is unknown. 



Development. According to M. Coste* the first appearance of the 

 lungs occurs in the shape of a small granulation, in 

 the median line, projecting from the anterior wall of 

 the oesophagus. This little mass is hollow within, and 

 communicates with the oesophagus by means of a 

 vertical slit which, eventually, by the dilatation of 

 its walls, forms the larynx and trachea. Soon this 

 central mass divides into two lateral portions to form 

 the two lungs. Still later, each lateral mass divides 

 itself up into an infinite number of vesicular vege- 

 tations, and is thus transformed into the parenchyma 

 of the lung. Finally, the process of development is 

 completed by the various metamorphoses of the em- 

 bryonic cells by which the several histological ele- 

 ments which compose the tissue of the respiratory 

 organs are formed. 



According to Bischoff,f and most of the German 

 embryologists, the lungs are first recognised in the 

 form of solid sprouting buds, which subsequently 

 become hollow by the melting down of their central 

 cells ; the remaining steps of the process being iden- 

 tical with those already described. 



gi e a b ndT U8 Sebaceous Glands. Sebaceous glands, which are 

 almost universally associated with the hair follicles, 



* Embryogenie Compare'e. Paris, 1837. (Ed.) 

 t Professor of Physiology in the t University of Heidelberg, Baden, 

 Germany. (Ed.) 



