42 THE BOTANICAL MAGAZINE. LVoi. xxxvi. No. 424, 



nucleoli, which are divided into two parts by a septum. I think 

 the binucleated cell of the control may have originated in this 

 fashion. 



The 50H preparations resemble somewhat Sakamura's material 

 treated with chloral hydrate 1; , but they more agree in. appearance 

 with tumor cells (especially with Kimura's case). 



General Appearance of 50H-preparations. 



Due to the development of mechanical tissues the tips of radicles 

 from irradiated seeds were harder than those of the controls. Very 

 few mitoses were found and almost all caces were anomalous, 

 chromosomes having become fragmentary and scattered in cytoplasm. 



Both the nucleus and nucleolus increase in size, though I have 

 not yet met with good transitional stages. Vacuolization of the 

 nucleoli is recognized in every case. There are cells, in which the 

 nucleolus has escaped from the nucleus. 



When the cytoplasm is vacuolated, it takes a weak haematoxylin 

 stain. There are many cells, whose protoplast has been separated 

 from the cell wall. The cytoplasm, when not vacuolated, stains 

 deeply with haematoxylin and has many granules stained deeply 

 with same dye (this is most conspicuous in the giant cells). In the 

 periblem tissue many cells are found in karyolytic condition and 

 others in pyknosis. I do not think that it is an artifact at all, 

 since the epidermis and neighboring tissues, both in longitudinal and 

 transverse sections, are disturbed comparing with the control. Even 

 in the tissue adjacent to the growing point pyknotic cells are found. 



I have noticed the decrease of chromatic substance in the 

 nucleus, reticular chromatic structure being found only in young 

 cells. Giant cells are very often met with (the nucleus enlarges so 

 as almost to fill up the entire cell, and, in these cases many 

 nucleoli are found scattered in the cytoplasm). Giant cells stain 

 deeply with haematoxylin and their nuclei have many nucleoli, which 

 stain weakly. 



Usuall}^ in the nuclei with more than two nucleoli, I have 

 noticed the decrease of chromatic substance (this agrees well with 

 Kimura's observation on tumor cells). 



1) Sakamuea, T. : Experimentelle Studien iiber die Zell-und Kernteilung mit 

 besonderer Rucksicht auf Form, Grofle und Zahl der Chromosomen. Jour. Coll. Sc. 

 Imp. Univ. Tokyo. Vol. 39, Art II, 1920. 



