152 THE CA>'ADIAN NATURALIST. [Vol. vi. 



or houjogeneous, but rather as always presenting some minute 

 molecular structure which distinguishes it from parts of glassy 

 clearness. Admitting that the form it assumes is not necessarily 

 that of a regular cell, and may be various and irregular in a few 

 exceptional instances, I am not on that account disposed to give 

 up definite structure as one of the universal characteristics of or- 

 U'anisation in livino; bodies. T would also suirsrest that the term 

 formative and nonformative, or some others, should be substituted 

 for those of living and dead, employed by Dr. Beale to distin- 

 guish the jDrotoplasm from the cell-wall or its derivation, as those 

 terms are liable to introduce confusion. 



EMBRYOLOGY. 



To the discoveries in embryology and development I might 

 have been tempted to refer more at large, as being those which 

 have had, of all modern research, the greatest effect in extending 

 and modifying biological views, but I am warned from entering 

 upon a subject in which I might trespass too much on your pati- 

 ence. The merits of Wolff as the great first pioneer in the ac- 

 curate observation of the phenomena of development were clearly 

 pointed out by Mr. Huxley in his presidential address of last 

 year. Under the influence of Bollinger's teaching, Pander, and 

 afterwards Yon Baer and Rathke established the foundations of 

 the modern history of embryology. It was only in the year 1827 

 that the ovum of mammals was discovered by Yon Baer; the 

 segmentation of the yolk, first observed by Prevost and Dumas 

 in the frog's ovum in 1824, was ascertained to be 2;eneral in sue- 

 ceeding years ; so that the whole of the interesting and important 

 additions which have followed, and have made embryological de- 

 velopment a complete science, have been included within the event- 

 ful period of the life of this Association. I need not say how 

 distinguished the Germans have been by their contributions to 

 the history of animal development. The names of Bischoff, 

 Beichart, Kolliker, and Remak are sufficient to indicate the most 

 important of the steps in recent progress, without attempting to 

 enumerate a host of others wdio have assisted in the great work 

 thus founded. I am aware that the mere name of development 

 suggests to some ideas of painful nature as associated with the 

 theory of evolution recently promulgated. To one accustomed 

 during the whole of his career to trace the steps by which evwy 

 living being, including man himself, passes from the condition of 



