preside]s^t's addbess, 29 



throughout the whole of the close season. The more vigilant 

 watching of the breeding places during the hatching period is 

 what is wanted. Some further regulations therefore would seem 

 to be required to be applied to the bird catchers. The difficul- 

 ties in the way however are considerable. 



Concerning the advances that have been made in natural 

 science, during the past year, the following may be specially 

 referred to. 



The views which Dr. Dohrn, of Leipzig, has recently put 

 forth, as to the details of the steps by which the vertebrate 

 stock arose out of an ancestry not very much unlike the exist- 

 ing Annelids, are of much interest. He first draws attention 

 to the correspondences between vertebrate and insect embryos, 

 which have been too little regarded in consequence of our de- 

 signating the nervous side in the one as dorsal, and in the other 

 as ventral. Yet the facts, that in both, the nervous system is 

 developed on the convex side of the embryo and acquires a 

 strong convex plexure anteriorly, and that the body cavity is 

 finally closed upon the side of the body opposite to the nervous 

 system point to a common origin at a comparatively high level. 

 The surface of the animal which is called ventral is determined 

 by the presence of the mouth on that surface, and if any verte- 

 brates had a mouth opening between the brain and the spinal 

 cord on the dorsal surface that dorsal surface would necessarily 

 become ventral. Since, moreover, the ancestors of the vertc- 

 brata must have had a nervous ring surrounding their gullet, it 

 would appear more reasonable to suppose that the mouth open- 

 ing had been changed in the course of (development than that 

 the situation of the nervous centres had been altered. "Wc are 

 thus led to look for traces of an old mouth opening on that sur- 

 face of the early vertebrates which correspond to our dorsal sur- 

 face, and to seek reasons for regarding our present mouth as u 

 comparatively modern development. Dohrn believes that the 

 old mouth passed through the nervous centres between the crura 

 cerebelli, or, more accurately, in the fossa rhomboidea, or fourth 

 ventricle, which is remarkable for being of greater proportionate 



