THE CELL AND PROTOPLASM. 105 



THE NUCLEUS. 



(a) Presence of a Nucleus. If protoplasm has 

 thus become a new substance in our minds as 

 the result of the discoveries of the last twenty 

 years, far more marvellous have been the dis- 

 coveries made in connection with that body 

 which has been called the nucleus. Even by the 

 early microscopists the nucleus was recognized, 

 and during the first few years of the cell doctrine 

 it was frequently looked upon as the most active 

 part of the cell and as especially connected with 

 its reproduction. The doctrine of protoplasm, 

 however, so captivated the minds of biologists 

 that for quite a number of years the nucleus 

 was ignored, at least in all discussions connected 

 with the nature of life. It was a body in the 

 cell whose presence was unexplained and which 

 did not fall into accord with the general view of 

 protoplasm as the physical basis of life. For a 

 while, therefore, biologists gave little attention 

 to it, and were accustomed to speak of it simply 

 as a bit of protoplasm a little more dense than 

 the rest. The cell was a bit of protoplasm with 

 a small piece of more dense protoplasm in its 

 centre appearing a little different from the rest 

 and perhaps the most active part of the cell. 



As a result of this excessive belief in the 

 efficiency of protoplasm the question of the 

 presence of a nucleus in the cell was for a 

 while looked upon as one of comparatively little 

 importance. Many cells were found to have 

 nucleii while others did not show their presence, 

 and microscopists therefore believed that the 



