j\Ir. II, J. Carter on the Organization of Infusoria. 121 



is not poruiittc'd, and the cell is here closed after the manner of 

 vegetable cells generally. What further strengthens the view that 

 tliere is in some Diatomcse {e.g. Navicula and Nitzschia) a layer 

 eorresjjonding to diaphane on the surface, is, that there is some 

 pielunsile anil transporting organ here, which undoubtedly has 

 tlie power of seizing particles that come in contact with it, and 

 of conveying them partially or wholly backwards and forwards 

 liuni one extremity of the frustulc to the other, or of retaining 

 them on any part of it stationarily. 



Moleculw. — We will apply this term to the minute, colourless 

 granules with which the sarcode is charged (fig. 3 b). They 

 differ in size, and are the first bodies that appear in it; but 

 whether they be of different kinds, have any particular office, or 

 undergo any further development, I am at present ignorant. 

 Aina'ba, Astasia (tig, 45), and Euglena (lig. 4G), in the earlier 

 part of their existence, respectively seem to contain nothing else 

 but this molecular sarcode, the nucleus, and contracting vesicle ; 

 afterwards the " granules " appear, and last of all the ovules, 

 both of which are developed in the sarcode amongst the molecular. 

 IJy the time the ovules have become fully formed, the sarcode and 

 its moleculie have died off, or disaj)peared (figs. 26, 46, 56). 



Granules. — This name is intended for certain large granules, 

 which make their a])pearance among the moleculse, and are cir- 

 culated round the abdominal cavity in the manner of the diges- 

 tive globules and particles of food (Hgs. 4 a, 5 c, 65 a). They 

 are of different sizes, but chietly characterized by being much 

 larger than the molecuke, few in number, of a circular, elliptical, 

 elongated, sub-round, or irregular shape, with thick dark edges, 

 apparently produced by obstruction to the passage of light, — 

 colourless, or of a yellowish-green tint. When large, and with 

 no other granular matters present but the moleculaj, they form 

 a striking feature in the interior of yi?wa?/;«, Vorticella, Oxytricha, 

 Paramecium aurelia, ike. ; but at times they are so insignificant in 

 size as to be undistinguishablc from the molecula*, even if present 

 at all. That they are not ovules may be satisfactorily seen when 

 both arc together; the dark, thick, and frequently irregular 

 edges aiul colourless state of the former contrasting strongly 

 with the thin, circular margin and faint yellow tint of the latter 

 (fig. 5 c). They apj)ear to increase in size and number with 

 the age of the infusorium, and, when fully developed, to remain 

 unaltered in size, though apparently somewhat shrivelled in 

 form, until their dissolution. On one occasion, while watching 

 the metamorphosis of an Oxijtricha (similar to, but not the 

 same as that described by M. Jules llaime*, and of which I 



* Ann. tics 8c-i. Nat. t. .\ix. p. \i)9, Zool. 1853. 



