i903-i9°4-] Remarks on Gloeocapsa. 131 



solution is blue in colour with a red fluorescence. The cells 

 of this Gloeocapsa are surrounded by a gelatinous, hyaline, 

 lamellated integument, which is formed by an excretion from 

 the cell, — not by a gelatinous modification of the cell wall. 

 There are no organs of reproduction in Glceocapsa, either 

 sexual or asexual : multiplication takes place by simple 

 vegetative cell-division. The cells immediately after division 

 assume a globular form. Each individual cell is furnished 

 with its own gelatinous integument. As each cell divides, 

 the daughter-cells also secrete an integument, whilst at the 

 same time they are surrounded by the integument of the 

 original mother-cell. By this method two or four cells are 

 produced, each with its own integument, forming a colony 

 within the much-stretched integument of the primary mother- 

 cell. This accounts for the peculiar lamellated appearance of 

 the colonies. Finally, the primary integument ruptures, 

 liberating the young cells. This process may be repeated 

 continuously, but at certain periods some of the cells develop 

 a spiny coat of cellulose in addition to the ordinary integu- 

 ment, forming a kind of resting -cyst. After a period of 

 quiescence these resting - cysts reproduce new colonies by 

 simple cell- division, after the manner of the genus. Occasion- 

 ally large colonies will be observed with the remains of the 

 spines upon the exterior integument, showing that they have 

 developed from a resting-cyst. What takes place within the 

 cell during this resting condition we do not know, but that 

 this stage at intervals is necessary to them is certain. By it 

 they gain renewed vigour. From it they emerge in a state 

 of rejuvenescence. The size of a colony of two cells, including 

 the integument, is in general 55juX 45|U. A colony of four 

 will be 85^ X 60/x.i 



Species of G-loeocapsa are found living in consortism with 

 fungi to form lichens. In the lichen Baeomyces roseus the 

 normal algal symbiont is a species of Cystococcus : this 

 occurs in the upper strata of the lichen thallus, whilst in 

 the lower portion the algal symbiont is Gloeocapsa polyder- 

 matica. It does not, however, appear to be constant in the 

 lichen thallus ; hence this form of consortism may be termed 

 contingent mutualistic symbiosis. 



1 A /u, or micron, equals the u-ji-oT of an inch. 



