156 Dr. F. Semon. On the Position of the [June 12, 



air, and must, therefore, be kept in damp surroundings. On the 

 other hand, excess of moisture encourages the growth of micro- 

 organisms in the mucus with which the eggs are frequently covered 

 when laid, and such foreign growths tend to the destruction of the 

 contents. 



On the whole, the general features of the development are closely 

 similar to those in other lizards ; I propose, therefore, to reserve the 

 details until a complete account can be given. I may, however, men- 

 tion that the pineal eye becomes a prominent feature at an early 

 stage. When pigment is deposited in the skin, an oval spot is left free 

 from it over the eye, and through this the dark pigment of the retina 

 shows clearly. Spencer* has stated that there is in Sphenodon very little 

 external trace of the pineal eye. This is true of the adult, but in the 

 recently hatched tuatara the pineal eye still shows as a dark spot 

 through the translucent skin over the parietal foramen. This I 

 have been able to observe even in a tuatara 8 inches in length. But 

 as the tuatara grows older the skin over the pineal eye becomes more 

 opaque, and though in some individuals the scantier development of 

 the pigment over the parietal foramen affords a feeble indication of 

 the position of the eye, yet in others the pigment is deposited there 

 as elsewhere, so that all external trace of the eye is finally lost. 



V. " On the Position of the Vocal Cords in Quiet Respiration of 

 Man, and on the Ren 1 ex-T onus of their Abductor Muscles." 

 By FELIX SEMON, M.D., F.R.C.P., Assistant Physician in 

 charge of the Throat Department of St. Thomas's Hospital, 

 and Laryngologist to the National Hospital for Epilepsy 

 and Paralysis, Queen Square. Communicated by Pro- 

 fessor VICTOR HORSLEY, F.R.S. Received May 25, 1890. 



(Abstract.) 



The investigation which forms the subject of this paper was under- 

 taken with a view of settling, if possible, the moot question whether 

 in man the larynx during quiet respiration plays an active role or not, 

 and, if the former, what is its function ? 



For this purpose the author has examined, by means of graduated 

 mirrors, the size of the glottis during quiet respiration in fifty adult 

 trained healthy persons, and, after death, in twenty-five adult bodies. 

 The method of the examination and the precaxitions necessary to 

 guard against possible fallacies are fully described in the paper. A 

 comparison of the measurements thus obtained shows that in less 

 than 20 per cent, the vocal cords during quiet respiration perform 



* ' Quart. Journ. Microsc. Science,' vol. 27, p. 176. 



