io8 Darwin^ and after Darwin. 



The next point we have to observe is, that in all 

 cases where a cell or a Protozoon multiplies by 

 way of fissiparous division, the process begins in the 

 nucleus. If the nucleus divides into two parts, the 

 whole cell will eventually divide into two parts, each 

 of which retains a portion of the origind nucleus, as 

 represented in the above figure. If the nucleus divides 

 into three, four, or even, as happens in the develop- 

 ment of some embryonic tissues, into as many as six 

 parts, the cell will subdivide into a corresponding 

 number, each retaining a portion of the nucleus. 

 Therefore, in all cases of fissiparous division, the 

 seat or origin of the process is the nucleus. 



Thus far, then, the phenomena of multiplication are 

 identical in all the lowest or unicellular organisms, 

 and in the constituent cells of all the higher or multi- 

 cellular. And this is the first point which I desire to 

 make apparent. For where the object is to prove a 

 continuity between the phenomena of growth and 

 reproduction, it is of primary importance to show — 

 ist, that there is such a continuity in the case of all 

 the unicellular organisms, and, 2nd, that there are all 

 the above points of resemblance between the multi- 

 plication of cells in the unicellular and in the multi- 

 cellular organisms. 



It remains to consider the points of difference, and, 

 if possible, to show that these do not go to disprove 

 the doctrine of continuity which the points of resem- 

 blance so forcioly indicate. 



The first point of difference obviously is, that in the 

 case of all the multicellular organisms the two or 

 more " daughter- cells," which are produced by division 

 of the '• mother-cell," do not wander away from one 



