422 



F. R. ROWLEY OX SOME POINTS IN THE STRUCTURE 



spindle-shaped corpuscles. In Diatoms prepared by Henneguy's 

 method for showing the centrosome, the pyrenoids, stained a 

 beautiful red by the safranin, stand out in marked contrast to 

 the pale substance[^of the chromatophore. 



Oil drops often occur in considerable numbers in the interior 

 of the cell (Figs. 2 and 5, oZ), especially in Diatoms cultivated 

 for some time with an insufficient supply of oxygen, as observed 

 by Liiders. Under these circumstances they appear in the form 



ch.l 



Fig. 4. — Portion of lobecl chromatophores ch.l. of SuHrella calcarata, 

 showing positions of the pyrenoids j^y. Above the chromatophores is 

 a network of protoplasmic fibrils, which exhibit oscillatory movements 

 in the living diatom. (After Lauterborn.) 



Fig. 5. — Nar'wula cuspidata. Surface view showing Biitschli's spherules 

 h.s., chromatophore ch, nucleus nu, nucleolus nly and oil drops ol. 

 (After Lauterborn.) 



of [several large, not always spherical, droplets, which may be 

 easily recognised by their solubility in sulphuric ether and 

 blackening with osmic acid. In addition to these undoubtedly 

 fatty globules, other structures occur in the interior of many 

 Diatoms, which, though optically very similar, differ in being 

 insoluble in alcohol and ether, in their behaviour when treated 

 w^ith osmic acid, and especially by their marked staining'capacity. 



