34S 



BOTANY 



the marine genus Schizonema they lie embedded in large numbers 

 in a gelatinous branching thallus, often over 1 dcm. in size. The 

 cells also display a great diversity of shape ; while generally bilater- 

 all\ r symmetrical, they may be circular or elliptical, rod- or weil^e 



shaped, curved or straight. The 

 structure of their cell walls is 

 especially characteristic ; it is com- 

 posed of two halves or VAI.YKS, 

 one of which overlaps the oilier 

 like the lid of a box (Fig. 3. />'). 

 The cells thus present two alto- 

 gether different views, according to 



Kiu. -274. I. icmophoru flubelln In. 

 Colony of Diatoms with liranched 

 gelatinous stalks. (After SMITH, 

 i'roni GOEBEL'S OrganofrapMe.) 



I-' in. -JT'i. Formation ( iiiixosi>uivs in 



i-ii-'iiliiln. J. Cell seen from tlie valve side. 

 /;. Two cells lyinj: alongside one another : their 

 ((intents have divided btto two danghtor eells, 

 .ach of which ]>ossesses two nuclei, i . /'. C,,n- 



.iu.^atinn in pain of the daughter calto to inrm 

 tlie auxosiHires, wliich at lirst contain four 

 nuclei. E, The two t'ull-j;iown .-uixosiMiies ; tin- 

 two larger nuclei in each have fuseil into one, 

 tin- two .smaller ones have disintegrated. (After 

 N U:STKX, x 500.) 



the position in which they are observed, whether from the .IKDLK 

 (Fig. 3 B] or VALVE SIDE (Fig. 3 A}. The two valves are so strongly 

 impregnated with silica, that, even when subjected to intense heat, 

 they remain as a siliceous skeleton, retaining the original form and 

 markings of the cell walls. The walls of the cells, particularly cm 

 the valve side, are often ornamented with numerous fine, transverse 



