Pec. i9io,}: .-.- KUWADA.-A CYTOLOG: STUD: OF OEYZA SATIVA. 269 



characterized by the contraction phenomenon or synizesis of 

 McCeung as an important stage in the maiosis, as has been 

 first maintained by Moore (8). In 1905 Strasburger (12) ex- 

 pressed a view, that at the synapsis the pangens undergo a 

 definite orientation through the mutual action of the paired 

 garnosomes, so that at the subsequent elongation of the garno- 

 somes, their pangens will get successive positions in such a way 

 as the homologous ones come close to each other. In my case with 

 Oryza satiya the elongation of the garnosomes takes place before 

 the synaptic contraction begins. Consequently we may say, 

 that the conglobation of the nuclear substance does not always 

 occur in a definite moment of the maiotic phase with respect to 

 other behaviors of the chromatin-threads. 



Moreover the fact that the synaptic contraction is a 

 natural process, does not necessarily imply that it has an 

 important biological significance. 



It is often mentioned that at the synapsis the nucleolus 

 makes its appearance in a lens shape. It seems to be probable 

 that a considerable amount of nutrition is needed during the 

 mitotic preparation partly as the sourse of energy for the 

 division, and partly as the building material. As the conse- 

 quence, there must be a strong metabolic interchange between the 

 nucleus and the c3 r toplasm. That such a strong metabolic inter- 

 change or some other special chemical process involved in the 

 maiotic prophase is the cause of this change of shape of the nucleo- 

 lus, is not improbable. In the living nuclei in the marginal cells 

 of the leaf of Elodea canadensis and in those of the leaf-hair of 

 Tradescantia virginica, Kohl (7) has observed the change of 

 shape of the nucleus, and the shifting of the nucleolus through 

 an increasing substance-interchange between the nucleus and 

 the cptoplasm as a consequence of the addition of asparagiri- 

 solution. The similar process may well cause the conglobation 

 of the chromatin-threads at the synapsis, especially because 

 they are very slender at this stage of prophase, and have likely 

 much smaller power of resistance for pressure than in the later 

 stages, where they are much thicker. In this connection we 

 may note that in some cases, as has been clearly described by 



