^^. 



THE BEGINNINGS OF LIFE. 



445 



'rated ' '^^'^ 

 ■Cities n, '' 



indurated 



I 



'." «f > Dia,„ 



e 



in thes 



^^ niasses of 



s 



a 



* E^glen^ have 

 iion— but most 

 are apt at cer- 

 large Diatoms, 

 mi may also te 

 ,Sj and that, in 

 torn varies ac- 



\ 



rontents of* [ 



dds(p.302);- 



cults, nantie 



des Naviculfs 



des miil'"" 



I 



I 



\ 



f 



s 



fas in t!'^ ^^ 

 Is between * 



E in P^' ^'°- 



d'autres (PI. 



fig. 



6) dont la carapace est moins 



organisee et moins minerale^'' Respecting the mode 

 in which the conversion of the recently-divided Euglen^ 

 takes place. Dr. Gros says 2; — ^Les vesicules derivees, 

 par des circonstances imprescriptibles, de vertes et 

 nucleolees qu'elles etaient, deviennent jaunatres et diri- 

 ment leur contenu en huit vesicules (PL F, fig. 2) sur 

 la paroi interieure ^ ; elles s'allongent par des nuances de 

 formes varices ; et par un elaboration de quelques jours, 

 elles arrivent (fig. 3, 4, 5) a donner ces physiognomies 

 si jolies de Navicules striees dont on a fait tant 

 d'especes systematiques. Encore une fois, les vesicules 

 derivees de telle forme et de telle division euglenienne, 

 donneront, suivant la saison, des Navicules difFe'rentes.' 

 And in illustration of this, he affirms that one set of 

 Euglen^ produced Navkula fulva and another allied 

 form^ whilst a different set became transformed into 

 N. Margarifera during the months of July, August, and 

 September, although they no longer underwent such 

 transformations in the months of December and 



r 



January. Whilst I have not myself been fortunate 

 enough to trace the actual origin of any of these large 



have, on several occasions, been struck 

 with the comparatively sudden appearance of very large 

 specimens (about -^^0'' in length) of Navkula UbriUs 



^ He also adds : — ' Vouloir essayer de representer toutes les formes 



serait vouloir donner Timage des grains de sable de Tocean. Ici comme 



aiUeurs, Timportant est de donner la filiation et non la pittoresqiie des 

 formes.* 



Diatoms, I 



Loc.cit., p. 336, 



See Fig. 85, a, h, c 



