274 THE PHENOMENON OF 



the chlorophyll-vesicles on those parts of the wall of the 

 mother-cell where the formation of the germ-cells occurs. 



Botrydium doubtless belongs to the same family as 

 Valonia, My observations on the formation of the germ- 

 cells of this .genus, already mentioned (pp. 1 28, 193), are 

 not sufficiently complete to decide whether it can be 

 properly cited as an example here. In Botrydium the 

 germ-cells are sessile all over the inside of the wall of the 

 vesicular epigaeous portion of the cell, placed pretty close 

 together, yet not in contact. They exhibit a rather con- 

 siderable difference of size in the same individual, which 

 seems to indicate a growth inside the mother-cell. Simul- 

 taneously with their completion the mother-cell swells up, 

 softens, and collapses. According to Kiitzing,* however, 

 the spores often germinate before the collapse of the 

 mother-cell, breaking forth on its surface as a granular 

 coating. 



2. The daughter-cells (mostly several, rarely only one) 

 are formed (around nuclei} free in the contents of the 

 mother cell. The term " free cell-formation," which 

 certainly meets most of the modifications to be examined 

 here, has hitherto been applied to many other kinds of 

 cell-formation already treated above. Looking at the 

 mere words, we may use this expression in two very 

 different significations, according as we intend to call the 

 (jell-formation free in its result or in its origin. In the 

 first sense we speak of free cell-formation in contrast to 

 the formation of connected tissue, under which circum- 

 stances the daughter-cells may stand originally in most 

 intimate contact with the mother-cell and with each other, 

 but not be grown together, or not so firmly that they 

 cannot finally become free by the rupture or resorption of 

 the mother-cell. We have seen such formation of free 

 cells under A. 2 (formation of the gonidia of (Edogonium, 

 of the pollen-grains, &c.), B. 2 (formation of the gonidia 

 of Ulothrix, Chardcium, &c.), D. 1 (Sciadium, Chytridi 



* On a new Botrydium, in ' Nov. Acta.,' xix, ii, 388, t. 69, 



