MOSS DEVELOPMENT. 9 
suggest that the Characeze are mosses which have been rendered 
abnormal by their aquatic habit, in which the formation of the 
non-sexual generation (sphorophore) has been altogether suppressed. 
(See Journal of Botany, No. 187, July, 1878, p. 202.) Dr. Vines, 
who has carefully discussed these relationships (Journal of Botany, 
No. 192, December, 1878, p. 355) would appear to be nearer the 
truth in regarding the Characez as an independent group inter- 
mediate between the Carposporeze and the Muscinez, thus linking 
the Thallophytes to the Cormophytes; in the structure of their 
vegetative and reproductive organs they resemble the cormoid 
Thallophytes on the one hand and the thalloid Cormophytes on 
the other. 
MOSS DEVELOPMENT. 
By W. STANLEY. 
\ OSSES are distinguished by a sharply defined alternation of 
generations, and are principally developed from true spores, as 
in the sporangia of ferns. 
Spores are described as reproductive cells, resulting from a 
vegetative process, excited by the act of sexual union, in conse- 
quence of which they arise on the second (non-sexual) generation 
(sporophore) which springs from the fertilized oosphere of the first 
(sexual) generation (oophore). 
Zygospores, Oogonia and Carpogonia, resemble the capsules of 
Mosses and the sporangia of ferns, and are the result of sexual 
fertilization, but their Zoospores, Oospores and Carpospores do 
not always give rise to such distinct alternation of generations, the 
second or non-sexual generation being a gradually increasing struc- 
ture, in many cases rudimentary, and in others entirely suppressed. 
In the typical Mosses the filamentous thallus, or Protonema, 
arises as a tubular bulging of the endospore, which lengthens con- 
siderably by growth at the apex and becomes divided, the divisions 
(septa) being oblique; branches are formed immediately behind 
the septa, and in their turn become divided ; the opposite portion 
of the endospore frequently gives rise to a transparent rootlet 
(rhizoid) which penetrates into the ground. Fig. 11. 
The Protonema is at first colourless, but the cells resting upon 
the ground soon assume a brown colour, while the upper cells 
develop abundance of chlorophyll granules, hence it is nourished 
independently of assimilation, and in some genera the densely 
matted filaments cover a surface of from one to several square 
inches in size. It generally disappears after it has produced the 
