150 NATURAL HISTORY SOCIETY OF DUBLIN. 



The outer wall of the parent cell, now enclosing the two elliptic 

 masses of contents, is still to be seen (fig. 5) ; it is thin, and hardly 

 presents a double contour. By degrees it seems to get more and more 

 faint, vanishing finally, probably by solution. 



Now begins the conjugation. Each elliptic mass derived from one 

 of the parent- cells passes over and becomes conjugated by complete 

 fusion with the corresponding opposite portions derived from the other 

 parent- cell (fig. 6). That is, although the two portions of each ori- 

 ginal parent-cell may now be regarded as physiologically distinct sister- 

 cells, being in fact daughter-cells without a special wall, they do not 

 conjugate with each other, but with the respective halves or daughter- 

 cells opposite to them. In other words, regarding the original parent- 

 cells as placed side by side vertically ; the upper half of the contents of 

 the left-hand cell becomes conjugated with the upper half of the con- 

 tents of the right-hand cell, whilst simultaneously therewith the lower 

 half of the contents of the left-hand cell becomes conjugated with the 

 lower half of the contents of the right-hand cell. Consequently, in 

 every case of conjugation in this plant there are two zygospores 

 formed, the four masses having become mutually amalgamated into 

 two. 



At an early stage each zygospore becomes surrounded by a halo 

 of mucus, which by degrees seems to become more and more dense and 

 more definitely bounded. Each nascent zygospore, at first of a more 

 or less irregular figure-of-eight shape, finally wholly coalesces to a 

 spherical form ; and each then acquires a definite, smoothly bounded 

 cell- wall, the contents being densely granular (fig. 7). 



Now, if observation ceased here we should have but an inadequate 

 and imperfect idea of the ultimate characteristics of these pretty and 

 singular zygospores. On keeping the specimens, it was found that they 

 were not destined to remain, like the zygospores of some species, abso- 

 lutely smooth, and without external decoration. Presently there 

 begins to arise what seems to be a kind of border of short linear spines, 

 when an optical section, as it were, is brought into focus (fig. 8). But 

 a more close examination shows that this is not a covering of spines, 

 but the beginning or basis of a honeycomb-like structure all over the 

 surface of the zygospore, and the spine-like lines are merely the angles 

 of the cells of the "honeycomb " structure, a little thicker than their 

 walls. By degrees this "honeycomb" structure rises and enlarges; its 

 cells become deeper and deeper ; then the walls of the cells of the 

 " honeycomb" become a little rounded externally, and each zygospore 

 is complete (figs. 9, 10). 



By focussing an empty cell- wall of a zygospore, one can see down 

 into the cavities or " cells" of the " honeycomb" structure at that part 

 of the globe nearest to the observer, and by degrees more and more 

 obliquely as they pass round to the circumference, where they are, of 

 course, as in the zygospore retaining its contents, seen sideways (fig. 

 11). By describing this remarkable structure as "honeycombed," I 

 do not mean to infer that the cells, or cavities, or interspaces are al- 



