Ivi THE BEGINNINGS OF LIFE. 



circumstances continuing the same, proceed in the same 

 direction for an unlimited time.' Dr. Hicks tells us still 

 further that — * When the soridia, undergoing this transfor- 

 mation, are placed in water, the mucous envelope becomes 

 much increased in diameter, the cells become more numerous 

 and smaller, and assume the appearance of Hetriatococcus 

 alpesiris. It proceeds sometimes to such extreme division 

 that the process seems almost indefinite, and the results 

 resemble Hematococcus theriacus, and minutissimus, Hass.' 

 Segmentation goes on, in fact, in various ways, and the pro- 

 portion that the mucous coat bears to the cell is exceedingly 

 variable. At other times a group of large oval cells is pro- 

 duced, each of them surrounded by a mucous layer, precisely 

 similar to the Palmoglea of Kiitzing {Coccochloris, Hassal). 

 The common mucous envelope soon disappears, and then 

 the contained cells rapidly subdivide and form an indefinite 

 mass resembling C. Brebissonii. Dr. Hicks believes that 

 even the Gkocapsa^ cells may and do, ' by the condensation or 

 desiccation of the mucous sheath and by the enlargement of 

 the green cell, ultimately revert to the form of the original 

 gonidium from which they arose.' He is disposed to believe 

 that the changes above detailed are by no means all that may 

 occur. Sometimes, indeed, the whole of the gonidial layer 

 of the lichen-thallus becomes converted into a Palmoglcea- 

 mass, which, after a time, is indistinguishable from other 

 masses produced from soridia. Observations of a somewhat 

 similar nature, though more limited in extent, had also been 

 previously made by J. Sachs ^-— of which, however, Dr. Hicks 

 was ignorant till at a late stage of his own investigations. 

 These have convinced him that the gonidium of a single 

 Lichen may, under the influence of suitable but varying 

 conditions, give rise to products absolutely resembling almost 



^ 'Botan. Zeitung,' Jan. 5, 1855. 



