176 Gardner—Studies on Growth 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 only 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 thisspirem 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 very 
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 SUBSTANCE TO THE MATERIAL OF 
THE SPIREM, OR CHROMOSOMES. 
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 
