ZYGNEMACEJS. 10 9 



" The first sign of a beginning spore -formation is that the cell widens 

 at its middle, so that this part resembles a cask. This widening is not, 

 however, equally powerful on all sides, but is stronger on one side than 

 on the other sides. At the same time the cell bends at its middle like a 

 knee, so that its two halves form a more or less obtuse angle with each 

 other. The point of the angle is placed where the before-mentioned 

 more powerful widening of the cell has taken place. Almost always the 

 formation of spores takes place at the same time in all the cells of a 

 filament. Then it regularly occurs that the cells bend alternately in 

 opposite directions, so that if cell No. 1 bends to the right, cell No. 2 

 bends to the left, No. 3 to the right, and No. 4 to the left again, and so 

 on. Consequently the cells in a filament-producing spores will form a 

 zig-zag line. Exceptions from this rule do, however, now and then 

 occur ; thus, that two cells abutting on each other bend in the same 

 direction, after which the two next bend in an opposite direction and so 

 on. When this occurs, the filament is gently curved like an S, alter-, 

 nately in two directions. When the spore-forming cell widens and 

 bends, the chlorophyllaceous band of the cell is often interrupted at its 

 middle part, by which the cell gets two chlorophyllaceous bodies instead 

 of one. The chlorophyll -coloured protoplasm now begins anew to give 

 proofs of its power of free motion. The chlorophyllaceous body (or 

 bodies if there are two) moves freely and rather quickly, from the other 

 parts of the cell to the widened middle part. When all of it has entered 

 this part of the cell, which has thus become almost quite filled with 

 chlorophyll-coloured protoplasm, the cell is divided into three cells by 

 two septa, appearing one on each side of the chlorophyll filled central 

 part. The cells formed by this partition are of two essentially different 

 kinds. The two lateral cells have very little living contents. All the 

 chlorophyll-coloured protoplasm is gone, and only the thin parietal layer 

 of protoplasm and some drops of oil are left. The rest of the contents 

 are only colourless cell-liquid. These cells have in fact filled their pur- 

 pose. They soon die, and remain, as mere skeletons of cells, attached 

 for some time (two or three weeks) to the central cell. The central cell is, 

 in contrast to the lateral cells, very rich in living contents, having re- 

 ceived all of the chlorophyll-coloured protoplasm of the mother-cell. It 

 is also designed to become the hypiiospore, through which the propaga- 

 tion of the species is to be affected. But before it becomes a complete 

 hypnospore it is to pass through several stages of development. The 

 first of these is that the cell-contents surround themselves with a new 

 layer of cellulose (me&osporium) within the original one (exosporium). 

 The mesosporium increases by-and-bye in thickness till it is considerably 

 thicker than both the exosporium and the endosporium (which appears 

 later). The mesosporium gets no sculpture (as is the case with so many 

 Mesocarpea*) it remains always smooth. But having been at the begin- 

 ning hyaline, it soon assumes a faint yellow colour. Within the meso- 

 sporium a new layer of cellulose forms during the first week ; this is 

 called endosporium. It remains always hyaline and very thin. During 

 this time the contents of the cell have also suffered a change. The 

 chlorophyll-coloured protoplasm, at least the greater part of it, has 

 changed into a fat oil, which is coloured in the same manner as the 

 mesosporium, i.e., a faint yellow. The hypnospore which is now 

 ready, shows a somewhat different shape, if regarded from different 

 sides. If regarded in the position it has when the curvatures of the 

 spore-forming filament are directed to the right and left of the ob- 

 server, the spore is, as a rule, non-symmetrically elliptic, with abrupt 

 ends, very seldom it is almost circular. The want of symmetry con- 

 sists in the spore being more convex on the side towards which the knee 

 of the mother-cell has bent. If we imagine the spore being turned a 

 quarter of a turn round its longitudinal axis, it appears somewhat 



