444 THE BEGINNINGS OF LIFE. 



v/hich two flagella are protruded i. Secondly, others 

 develop a brownish and slightly indurated envelope, 

 marked by dotted lines disposed in a spiral manner ^ j 

 these forms being pointed at both extremities, motion- 

 less, and without flagella. And thirdly, others, also 

 motionless, assume a spheroidal or beautifully ovoidal 

 form, whilst their diaphanous and indurated testa 

 becomes faintly striated after the fashion of a Diatom. 

 The chlorophyll corpuscles contained in these forms 

 also fuse into two or three large central masses of a 

 very bright green colour 2. 



7. Transformation Into Diatoms. After Euglenas have 

 undergone two or three processes of fission — but most 

 frequently after the third — some of them are apt at cer- 

 tain times to become converted into large Diatoms. 

 Dr. Gros states that similar transformations may also be 

 observed in specimens of Chlamydomonas, and that, in 

 each case, the precise pattern of the Diatom varies ac- 

 cording to the size and the nature of the contents of the 

 vesicle which becomes transformed. He adds (p. 302) : — 

 'Si les vesicules sont fortes, bien vesicules, nanties 

 d'une certaine masse, on en voit d£river des Navicules 

 striees. Ailleurs, on en voit deriver des millions 



^ See Gros, loc cit., PI, E, figs. 2, 12, 14, 15, 17, 



"^ See Gros, loc. clt., PL D, fig. 3. The actual arrangement of the spiral 

 Imes was different in different specimens. Sometimes, as in the figure 

 above referred to, the lines were equidistant, but at other times they were 

 arranged in sets of twos or threes, with broader intervals between them. 



^ Such bodies very closely resemble fig. 6 of PI. E in Dr. Gros' 

 Memoir. 



