THE MICROSPORANGIUM 



41 



biennis, Gates (1911) observed a frequent migration of chromatic 

 material from one microspore mother cell into another and called 

 it cytomixis. Since then it has been reported in several other plants, 

 and while it is most frequent between the synizesis and diakinesis 

 stages, it may sometimes occur even during the interkinesis stage, 

 i.e., after the first meiotic division has been completed. In Lathraea 

 (Gates and Latter, 1927), which is an instance of this kind, the 

 microspore mother cells do not round up but remain in close contact 

 with one another. During interkinesis the nuclei of the two dyad 

 cells occupy an eccentric position near the cell wall so that the 



A B 



Fig. 32. Sterilization of part of sporogenous tissue in anthers of Sivertia perennis. 

 A, anther lobe at microspore mother cell stage. B, same, at microspore tetrad 

 stage. {After Guerin, 1926.) 



chances of cytomixis are increased. In Coreopsis tripteris (Gelin, 

 1934) cytomixis may also occur at the close of the meiotic divisions 

 but the multinucleate cells formed in this way again break up into 

 smaller units consisting of one or two nuclei. 



In some plants individual chromosomes, or groups of chromo- 

 somes, or even whole spindles are said to be carried from one cell 

 into another. It is believed, however, that it is a pathological 

 phenomenon, or that such appearances are caused by faulty fixa- 

 tion. Woodworth (1931), who used smear preparations of anthers, 

 states that cytomixis was common when a little extra pressure was 

 used in squeezing out the microspore mother cells. Further, such 

 abnormalities were found to be more frequent in hybrids than in 

 other plants, and he attributes this to an "innate unbalance" in the 



