Significance of the Nuclear Skein 233 



their task being to control and to direct the life functions 

 of the cell, and to that end they must be able to enter into 

 as free a contact as possible with the granular plasm. An 

 arrangement in rows, at least of ,those bearers that are to 

 become active, is the necessary condition thereto, and it 

 is evidently reached by means of the elongation of the 

 threads and the formation of the skein. 



In order to make possible an orderly retreat of the 

 individual threads out of the tangle of the skein, every 

 thread is firmly attached by one end to the nuclear wall. 

 It retreats to this point, which is at the same time the point 

 at which its two halves, during cell-division, are pulled 

 apart after the splitting. The whole regularity of the 

 process would be hard to explain without this firm im- 

 plantation of the individual nuclear threads, as demon- 

 strated by Boveri. Where the nuclei are sinuate and the 

 nuclear threads are attached in the individual curves, the 

 conditions are specially clear. 



In the species of locust, Brachystola magnet, Sutton 

 found the same implantations of the nuclear threads on 

 the curves of the nucleus. But here every thread, of 

 which there are eleven in every pronucleus, forms a skein 

 after the cell-division. These skeins of one and the same 

 nucleus remain separated from each other for a long time, 

 and the independence of the chromosomes can hence be 

 directly demonstrated, even at the stage of the skein. This 

 locust has also proven very instructive in another point 

 of Button's studies. 



In general, one finds the individual chromosomes to be 

 of unequal length in the most various nuclei. But, in the 

 species of locust mentioned, this length occurs in such a 

 characteristic manner that the chromosomes can be easily 

 recognized in the successive cell-divisions. The pictures 



