ZYGNEMACER, 101 
Mr. Archer has thus described the present plant :—“ Cells short, vary - 
ing from nearly quadrate to three or four times longer than broad, 
according to the interval of time elapsed since division ; the contents 
bright herbaceous green, forming an axile compressed band (never sepa- 
rate stellate chlorophyll bodies as in Zygnema) ; the conjugation taking 
place by short wide processes, which, along with the shortness of the cells 
or joints, gives the pair of conjugating filaments somewhat the appearance 
of aperforated ribbon-like structure; the total cell contents of each 
pair of conjugating joints became massed together into an elliptic zygo- 
spore within the inflated transverse tube; the longer diameter of the 
zygospore placed vertically to the length of the filaments; the cavity 
occupied thereby not shut off by any septum from the cavities of the 
parent joints. It was evident that there was no septum separating the 
zygospore from the cavities of the parent cells, but it lay freely in the 
inflated transverse process, though frequently in contact with its walls 
about the middle.” 
Plate XZ1. fig. 2. a, sterile cells X 400; 6, fertile cells with zygo- 
spores X 200. 
Sub-Family 2. Masocaresa. 
Cells cylindrical, united in threads, with axile plates of 
chlorophyll. Zygospore the shape of the mother-cells; not 
contracted, separating by three to five partitions into a central 
firm-walled resting spore, and two or four lateral decaying 
cells, 
The method of conjugation and spore-formation in the Mesocarpe was 
not thoroughly understood until it was investigated and explained by 
De Bary (“ Conjugaten,” 1858), who first recommended the separation 
of the Mesocarree from the Zygnemee, and their recognition as separate 
families. His exposition of the conjugation of the Mesocarpee is thus 
summarised by Wittrock* in a memoir submitted to the Swedish Academy : 
—‘ Two cells grow together in the common manner by conjugation out- 
growths, and a resorption of the double septum between the two conjuga- 
ting cells takes place. By this a cruciated or H-shaped double cell is 
formed, in which at first no other change takes place than that the canal 
of conjugation is somewhat widened, and that the chlorophyll-coloured 
part of the contents of the double cell moves into the canal of conjuga- 
tion, and into the parts of the double,cell nearest to the canal. This 
cruciated or H-shaped cell, thus formed immediately by the conjugation, 
De Bary regards as the zygospore of the Mesocarpee, and gives it the 
character of being ‘not contracted’ in contrast with the zygospore of 
Zygnemee and Desmidiew, This zygospore exists, however, only for a 
very short time as such. The above-named moving of the cblorophylla- 
ceous bodies (not of the whole protoplasmic mass) into the connecting 
canal having been accomplished, the zygospore is divided by two or four 
septa into three or five cells, of which one, the central one, is a hypno- 
spore, rich in chlorophyllaceous protoplasm (and later in oil), whilst the 
two or four lateral cells, containing no chlorophyllaceous protoplasm, are 
sterile, and soon going to die. Thus the MWesocarpee have, according to 
De Bary, spores of two kinds, namely (1), zygospores, which are formed 
ioe On the Spore-formation of the Mesocarpex.” By V. B. Wittrock. Stockholm, 
