EXPLANATION OE THE PLATES. 



PLATE I. 



Palmogl(Ba macrococca, Klitzing ?* 

 (CoQcochloris Brebissonii, Thwaites). 



All the figures are from specimens from the Hollenthal, 

 near Freiburg. The figures 21 — 28 and 1 — 13 of 

 PL II represent the conjugation of the cells, and the 

 consequent formation of the spores, as described at 

 pp. 135, 202, and 285 of the text. Magnified 350 diam. 



Fig. 1. A ceU with a distinguishable gelatinous envelope. 



Fig. 2. A cell which has attained the maximum of 

 longitudinal growth. 



Fig. 3. A cell beginning to divide. 



Fig. 4. A pair of cells produced by division, the two 

 portions still in contact. 



Figs. 5 and 6. The same, but the two daughter-cells, 

 still enclosed by the common enveloping membrane of 

 the mother-cell, have already separated, without however 

 exhibiting distinguishable special envelopes. 



Fig. 7. Two cells, considerably elongated and possessing 

 special coats, enclosed by the common mother-envelope. 



Fig. 8. A cell of moderate length with two vesicles in 



* The species of the genus Palmogl(Ba, established by Kiitzing, cannot be 

 certainly determined either by the characters given in the ' Spec. Algarum,' 

 or by tne fibres given in the ' Tabulae PhyoologicEe.' In the species 

 represented in our plate, the jelly-like cell-envelopes are sometimes dis- 

 tinguishable singly, sometimes not, which renders doubtful evert the section 

 in which we are to seek the species. The germ-cells vary in length from 

 55 to j'j miUim., average, therefore, t^j to ^^ of a line, so tliat the distinctions 

 founded on size, given by Kiitzing, likewise furnish no safe criterion. 

 Prom the variability of the characters, it is not improbable that many of the 

 species brought forward by Kiitzing, in particular P. rupestris, macrococca, 

 vesiculosa, lucida, rnfescens, and crassa, wiU have to be combined as forms of 

 one and the same species. 



