288 G. E. COGHILL 



the experimental evidence of the development of function in the 

 organ. 



4. Response to olfactory stimulation 



In the anatomical part of the paper it was noted that the 

 olfactory nerve is well established in the early swimming stage. 

 Preliminary experiments were made in 1912 to discover whether 

 olfactory stimuli in any way stimulate movement. Pellets of 

 various substances were enclosed in gauze and placed in the 

 center of flat dishes about 9 by 13 cm. In these dishes embryos 

 somewhat older than the early swimming stage were distributed 

 in cistern water. Pellets of pure gauze were used as checks. 

 In other pellets were placed, egg masses, fresh algae and debris 

 from aquaria which emitted a strong odor. The embryos in all 

 the dishes were frequently agitated to discover whether the 

 olfactory organ had any influence in directing movements stimu- 

 lated from other causes. Over thirty embryos in the different 

 test dishes and the same number in the check dish were kept 

 under observation for three hours without the manifestation of 

 any tendency on the part of the specimens to collect in the 

 vicinity of the odiferous substance. A number of experiments 

 of this kind gave no further suggestion of olfactory reflexes. 

 Experiments of this kind, however, should be carried further to 

 determine whether other substances may not be found which 

 would stimulate olfactory reactions, either directly or by rein- 

 forcing or inhibiting other responses. It has been noted how- 

 ever, that, although olfactory neurones have grown into the 

 brain in considerable numbers, the olfactory epithelium is very 

 poorly differentiated in the ages under consideration. 



5. The auditory and lateral line organs 



The relative development of the lateral line system of organs 

 and nerves during this period arouses inquiry concerning their 

 function. In the postauditory region this system develops dis- 

 tinctly in advance of the general cutaneous component in both 

 its central and its peripheral relations. Even in the preauditory 



