PRIMORDIAL UTRICLE. [ 536 ] PRIMORDIAL UTRICLE. 



The preservative liquid must not be capa- 

 ble of exerting any action upon the cements 

 used in making or closing the cell. 



If chloride of calcium or glycerine be used 

 as the preservative liquid, when the first 

 coat of liquid cement used to close the cell 

 has become dry, the slide and cover should 

 be washed gently with a sponge and distilled 

 water, then dried with blotting-paper or a 

 silk handkerchief, and the next coat of var- 

 nish applied. 



The deeper the cell, the less the chance 

 of the object being spoiled. 



As soon as objects are mounted, the slides 

 should be labelled with a square or circular 

 piece of paper pasted upon them, the name 

 and other particulars being expressed in 

 writing. The name, &c. may also be 

 written upon slides with a diamond, but the 

 paper labels should always be used, other- 

 wise much time will be lost in searching for 

 and distinguishing particular objects in the 

 cabinet. 



BIBL. Treatises upon the Microscope; 

 Harting, Het Mikroscop, Edinb. Monthly 

 Journ. 1852, or Ann. Nat. Hist. 1852. x. 311; 

 Reckitt, Ann. Nat. Hist. 1845. xvi. 242; 

 Berkeley, ibid. 1845. xvi. 104 ; Ralfs, Brit. 

 Desmid. ; Smith, Brit. Diatom. ; Corti, 

 Siebold and Kolliker's Zeitschr. iii. 134; 

 Griffith, Ann. Nat. Hist. 1843. xxi. 113; 

 Tulk and Henfrey, Anatomical Manipula- 

 tion, 1844. p. 128. 



PRIMORDIAL UTRICLE (utriculus 

 primordialis, primordialschlauch). This 

 name has recently come into general use, at 

 the suggestion of Mohl, to indicate a pecu- 

 liar portion of the contents of the cellulose 

 sac constituting a vegetable cell; by that 

 author it is regarded as a distinct structure, 

 by others its separate existence is doubted, 

 while recently it has been proposed by 

 Pringsheim to transfer the name to a struc- 

 ture different in its nature from that which 

 Mohl has described as his primordial utricle. 

 As the formations comprehended under this 

 name are of great importance in the deve- 

 lopment of vegetable cells, a little detail 

 must be entered into in explaining this sub- 

 ject. 



If a cell of the pulp of any succulent fruit, 

 a cell of yeast, or cells in sections taken 

 from the delicate nascent tissues of any 

 growing part of plants, are placed in water, 

 the entire contents will soon be seen to 

 retract from the cellulose wall, leaving a 

 clear space, filled with transparent liquid, 

 between the latter and a sharply-defined line 



bounding the contracted or coagulated con- 

 tents (PL 38. figs. 1, 2, 10-12). The addition 

 of tincture of iodine makes the conditions 

 still more clear. If the parent-cells of 

 pollen-grains or spores are treated thus, 

 just before the development of the cellulose 

 wall of the special parent-cells (see POLLEN), 

 the four portions of the contents of the 

 parent-cell contract and separate, and each 

 portion, containing its own granular struc- 

 tures and nucleus, appears bounded by a 

 well-defined line (fig. 612). This well- 



Fig. 612. 



CM- 



Fig. 612. Parent- cells of pollen-grains just after the 

 separation of the contents into four portions, treated with 

 iodine. CM, the parent-cell. P, the protoplasmic por- 

 tions, each with a nucleus and a well-defined outline 

 at the surface of the primordial utricle. Magnified 250 

 diameters. 



Fig. 613. Cells of Protococcus multiplying. The green 

 granular contents are bounded by the definite outline of 

 the primordial utricle ; the primary and secondary cellu- 

 lose parent-cell membranes are represented as separated 

 from each other. Magnified 400 diameters. 



defined line presents in this condition the 

 appearance of a delicate membrane or pellicle 

 enclosing the entire contents. The action 

 of acids, or spirit, and iodine, reveals the 

 existence of a similar set of conditions in all 

 actively vegetating cells, and in most cases 

 a more or less thick viscous layer of the 

 protoplasm is found lining the cellulose wall 

 before the application of the reagents. Since 

 the line indicating the boundary of the con- 

 tents cannot be distinctly seen until the 

 contents have retracted from the cellulose 

 wall, and since the protoplasm is always 

 coagulated by the action of the reagents, it 

 is a subject of discussion whether the film 

 forming the well- denned line on the surface 

 of the contracted contents is a true structure, 

 or only a pellicle produced by the coagula- 

 tion of the surface of the protoplasm, just as 

 a <f skin " forms over size, or other similar 

 substances when they dry up in the air. 

 There is great ground for believing the latter 

 view to be correct, but the term primordial 

 utricle, as used by Mohl, is applied to the 

 protoplasmic layer lining the cellulose wall, 



