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nor are their mother-cells clearly marked off from thè ordinary ve- 
getative thallus cells, as in thè Eu-Floridea) generally. 
In thè filamentous Bangia thè whole contents of thè mother-cell 
which may he any celi in thè filament, escape as a neutral spore, a 
«monospore». Occasionally thè mother-cell first divides into two or 
four cells each of which becomes a neutral spore, a ((bisporen or 
« tetraspore ». 
In Porphyra thè formation of thè neutral spores is essentially 
thè same as in Bangia, though bere each mother-cell normally 
gives rise to two or four spores by one or two Successive divisions. 
In Erythrotrichia a spore mother-cell gives rise to a spore by a 
transforraation of part of its contents which part escapes as a spore. 
The part of thè mother-cell remaining grows considerably, and thè 
formation of another spore takes place, thè process being soraetimes 
repeated several times. 
On comparing thè neutral spores in thè two groups Schmitz will 
not allow that they are homologous structures and emphasizes thè 
difference he sees in their mode of formation, stating that in thè 
Eu-Florideae thè tetraspores are due to thè internai division of thè 
contents of thè thallus mother-cell, thè tetrasporangium, but that in 
thè Bangiacese thè neutral spore is formed from thè whole of thè 
contents of thè single thallus celi, or where several spores are for- 
med they are found side by side, each from its own thallus celi. I 
do not think one can attach much value to this distinction. If thè 
celi of thè thallus in thè Bangiaceous genus, which divides into two 
or four cells were so to divide that normally one only of its divi- 
sions became a neutral spore and thè rest became ordinary vegeta- 
tive thallus cells there would be considerable justification for Schmitz’s 
distinction. As however thè two or four cells derived by division 
from thè originai thallus celi become neutral spores, this celi is, it 
seeras to me, thè mother-cell of thè two or four derived cells and in- 
directly of thè neutral spores formed from their contents just as is 
thè tetrasporangium thè mother-cell of its four tetraspores, though 
thè connection is not so ijitimate in thè former case. 
The formation of neutral spores in Erythrotrichia by a kind of 
(( gemmation », as described by Berthold is not dissimilar to thè inno- 
vation of tetrasporangia as described by Harvey Gibson in Rho- 
dochorton Rothii, Kdig, 'm which species thè «stalk-cell» grows up 
R. Harvey Gibson; Journ. Linn. Soc. Bot. voi. 28, PI. 34. 
