1/6 Gard>icy — Studies on Groivtli and Cell 



mon to see this relation at two or three points (Fig. 9). That 

 this is an actual dipping in and not a mere superficial relation, 

 can not onl)- be plainly seen, but the staining relations next to 

 be described prove that this must be the case. The thread 

 being in connection with the nucleolus, ceases to absorb crim- 

 son stain, as the nucleolus transfers itself into the thread. 

 This thread, as it receives the nucleolar material, becomes 

 thicker, and we have finally a thick thread — the spirem. All 

 stages of transference can be seen. First, there is a large 

 bluish black nucleolus and a long bright bluish-crimson thread ; 

 the thread becomes darker, the bluish color becoming more 

 predominant than the crimson, and then stages are reached 

 when it is difficult to perceive the crimson at all. Finally we 

 have the completed spirem stained just as was the nucleolus 

 (Fig. 11). And this spirem can now be described as a thick 

 bluish black, irregularly wound thread (Figs. 12 and 13), 

 consisting of linin with more deeply stained chromatin granules 

 placed at intervals along its course. As the nucleolus is 

 gradually transferring its contents to the thread, it naturally 

 becomes smaller, and when the spirem is complete, the nucleo- 

 lus has disappeared. One of the last stages in which the 

 spirem is almost complete, and the nucleolus therefore verj' 

 small, is shown in Fig. 11. Such stages, as one would 

 expect, are rather difficult to find, for the spirem thread becom- 

 ing darker and thicker as the nucleolus becomes smaller, is apt 

 to obscure the nucleolus from view. The spirem now divides 

 transversely into the chromosomes. 



Relation of Nucleolar SuBSTA^•cE to the Material of 

 THE Spirem, or Ciirojioso.mes. 



From the above observations, it can be stated that without 

 doubt the chromosomes have derived at least a large part of 

 their material from the nucleolus. As the spirem becomes 

 more and more deeply stained, we know this staining relation 



