Embryology. 113 



beautifully ordered that to my mind they constitute 

 the most wonderful if not also the most suggestive 

 which have ever been revealed by microscopical re- 

 search. It is needless to say that I refer to the 

 phenomena of karyokinesis. A few pages further on 

 they will be described more fully. For our present 

 purposes it is sufficient to give merely a pictorial 



FIG. 29. Successive stages in the division of the ovum, or egg-cell, of 

 a worm. (After Strasburger.) a to d show the changes taking place in 

 the nucleus and surrounding cell- contents, which result in the first 

 segmentation of the ovum at e : f and g show a repetition of these 

 changes in each of the two resulting cells, leading to the second seg- 

 mentation stage at h. 



illustration of their successive phases ; for a glance at 

 such a representation serves to reveal the only point to 

 which attention has now to be drawn namely, the 

 immense complexity of the processes in question, and 

 therefore the contrast which they furnish to the simple 

 (or " direct ") division of the nucleus preparatory to 

 cell division in the unicellular organisms. Here, then 

 * I 



