3o2 LESTER W. SHARP 



LuNDEGÂRDH (lo) has also observée!. Since the observation froin which 

 Gates (12) recently concluded that the spindle is a relatively stable struc- 

 ture was made upon tixed material \ve cannot attach to it any great value. 

 The séparation of the chromosomes is yet to be explained. 



Anaphase. 



The phenomena of the anaphase hâve been so fully described by other 

 authors that they will hère be given very brief treatment. The two halves 

 of each double chromosome begin to separate at the point of insertion on 

 the spindle, fig. 26, 27, and gradually move away from the equatorial 

 plane, fig. 28, 29. Fig. 30 shows the séparation of the halves of a long 

 chromosome both of whose ends were lying on the same side of the equa- 

 torial plane, such as the lowermost chromosome of fig. 25. 



Thèse events correspond in every particular to the 1 écartement dicen- 

 trique '^ described by Grégoire (12). Dehorne (ii) concluded from his 

 work upon Salamandra and Allium that the anaphase consists in the 

 simple séparation into two lots of entire but secondarily split chromoso- 

 mes, a statement which has been given adéquate answer by Muckermann 

 (12) in his work on Salamandra itself, and by Grégoire (12) in his récent 

 very detailed description of the metaphase and anaphase in Galtonia, Tril- 

 liiitn and Allium. 



Just before the daughter chromosomes become completely separated 

 they are seen to be connected by small bridges of the chromatic material, 

 fig. 31. Since the chromosomes are moving apart at this time at least 

 thèse anastomoses are certainly due to the drawing out of the viscid matter 

 of the chromosomes, and are not sent out after the manner of pseudopodia. 

 This fact is to be borne in mind in interpreting the anastomoses formed at 

 other stages, notably at the telophase, which will soon be discussed. 



The daughter chromosomes finally become entirely free from one 

 another and draw together in two groups at the pôles, fig. 32. At this time 

 the corresponding chromosomes are easily distinguished, especially in the 

 case of the transversely segmented ones. They soon contract into extremely 

 compact masses, the individual chromosomes being seen only in the 

 most favorably stained préparations, fig. 33. This r tassement polaire « 

 (Grégoire and Wygaerts, o3) has been held by Lundegârdh (12 a) to be 

 an artificial phenomenon due to the tixing reagents. With this opinion the 



