CYTOLOG rCAL STUDIES OX CEREALS AND THEIR HYBRIDS. ]81 



are difficult to make out (PL XL Fig. 48), on account of the abundance of chromatin. 

 The chromosomes in the poles of the spindle do not alveolate as in barley and wheat, but 

 turn to spirem and arc arranged as in Fig. 51 of PL XI. 



Now, the question is whether chromosomes in the daughter nucleus alveolate or 

 stretch to spirem. Strasburger, Mottier, etc. held the latter opinion, while Gregoire and 



to my own observations, however, in barley and wheat, they alveolate, while in rye they 

 turn to spirem, indicating the existence of these two modes even in plants belonging to 

 the same family. 



In all my materials the homootypic division occurs as usual, in whirl, also the 



matin hindered the observation in the first division (PL XI. Fig. 52, 53; PL XII. Fig. 68, 

 69). The chromosomes, which form the grand-daughter nucleus alveolate or turn to 

 spirem in a similar manner as in the case of daughter nuclei (PL X. Fig. 31 ; PL XL 

 Fig. 54; PL XII. Fig. 70). 



Reduction Division in Wheat X Rye. 



The heterotypic division in plant hybrids began to receive great attention from cyto- 

 logists, since the publication of Rosenberg's paper on Drosera-hybrid in 1903, and many 



the absence of fertilizing power in the pollen of several hybrids is not caused by the 

 abnormal reduction division, but by their degeneration based on the deficiency of cytoplas.na. 

 Rosenberg ('03, '04, '09) studied the Drosera hybrid— Drosera longifolia (40 chromosomes) 

 x D. rotundifolia (20 chromosomes)— and found 20 double chromosomes and 10 single 

 chromosomes at reduction division. Gates ('09) avers that in the hybrid Oenothera lata 

 (14 chromosomes) x O. gigas (28 chomosomes) there arises 20 double chromosomes and a 

 single one, or simply 20 double chromosomes. 



The wheat-Kve hybrid, which I have studied, was crossed by Mr. Masanao Ito in 

 the summer of 1908 in the College Experimental Field. The seeds thus obtained were 



('07, p. 144 ff.). He ('04) discovered that the hybrid does not produce any pollen and is 



