TO BOTANICAL GAZETTE [jantjary 



show that this loosely tangled mass consists of lightly colored threads 



granules 



in 



and 



on the 



irregularities in thickne 



material 



and more loosely a.^^< 



That the parts of the thread in this stage are double is fairly dis- 



i/a) m tangential sections of the nucleus; undoubtedly 



cemible (fig 



come 



represented in fig. i6 as originating from the transformation 

 reticulum; therefore this double part of the thread cannot be 



independent 



as 



run 



fusing. Whether they are completely fused or not could not be 

 determined but their association is very close. These 



masses 



come more tightly drawn toerether and 



ball which seems to be the climax of the synaptic stage {fig. i8). 



Formation of heterotypic chromosomes.— The course of the 



thread or spirem is irregular in the synaptic stage; it is twisted and 

 generally much curled, but there are present several parts of the 

 spirem w^hich run comparatiyely straight across the contracted ball of 

 the spirem from near the nuclear wall with which it lies in contact. 

 The loops happen to be formed near the peripher}^ of this contracted 

 mass, but they have nothing special to do with the formation of 

 chromosomes. 



In the majority of cases the nucleoli seem to unite into one, which 

 becomes caught in the tangled mass in the early synaptic stage, gener- 

 ally far from the nuclear membrane, and its spherical form persists. 



The spirem of this stage shows a relatively smooth structure and 

 it is not easy to distinguish its double nature throughout, probably 

 on account of the close association of the two independent parts; but 

 tangential sections reveal that the parts of the spirem are unmistak- 

 ably composed of two threads nmning side by side, often diverging 

 rather widely {fig. 19). Tt seems highly probable that we see here an 

 indication of the separation of two threads which were first observed 

 in the presjuaptic stage {figs. 16, i6a) and entered into svnaDsis. as 



