ARCHER, ON PALMOGL@A MACROCOCCA. 125 
envelope the cell-contents, very dense and coarsely granular, 
the latter ultimately becoming considerably retracted from 
the outer wall and surrounded by an inner, finally yellowish 
or brownish coat, forming the actual spore, which presents to 
view a four-, five-, or six-sided, or a somewhat circular outline, 
sometimes somewhat flattened at certain sides, slightly en- 
larged or thickened at the angles, and often presenting on 
the general surface a slightly undulate or somewhat granular 
appearance, due to the presence of little superficial promi- 
nences. When showing four sides, I presume the inner spore 
may be of a cubical or prismatie figure, and when five- or six- 
sided, irregularly polygonal, but it appears sometimes of an 
irregularly rounded, very indefinite form. I have not seen, 
however, a triangular form. 
Measurements.—Length of cell, 5, to —1,; breadth of 
cell, =75,; length of zygospore, ;4, to ;4,; breadth, 1, 
to <1, of an inch. 
Plate I, fig. 1, cell in which the chlorophyll-plate cannot 
be seen; either the remaining contents are too dense, or the 
edge view of the plate is not towards the observer. Fig. 2 
shows edge view of chlorophyll-plate, with nucleus (?). Figs. 
3, 4, accidental forms and positions of the chlorophyll-plate. 
Fig. 5, cell about to divide; the chlorophyll-plate divided ; 
its immer ends bluntly rounded. Fig. 6, the cell divided. 
Fig. 7, two cells about to conjugate. Fig. 8, two such cells 
in contact, the parent-coats slipping off. Figs. 9 to 13, various 
degrees of advancement of conjugation. Fig. 14, zygospore 
formed, with mucous investment. Figs. 15 to 19, various 
mature zygospores. 
Now, as regards the position of the genus to which this 
plant belongs, inasmuch as the mode in which the reproduc- 
tive process is carried out in any organism is always—and 
doubtless rightly—yregarded as of more importance than 
vegetative structure in deciding affinity, the fact that in these 
forms reproduction is by conjugation most strongly points to 
a close relationship with the Desmidiaceze and with the 
Zygnemaceze; and in this genus the process is essentially 
that which characterises those families. On the other hand, 
the gelatinous nature indicates considerable affinity with the 
Palmellacez ; but, with the exception of Palmogloea, I am 
not aware of conjugation having been found in any other genus 
of that family, though zoospores occur in some, while in 
regard to others Professor Kiitzing’s* and Dr. Hicks’ inte- 
* Kiitzing’s “Die Umwandlung niederer Algenformen in héhere,’ &., pub- 
lished in ‘Natuurkundige Verhandelingen van de hollandsche Maatschappij 
der Wetenschappen an Haarlem,’ 1841. 
