84 Mr. H. J. Carter on Fecundation in QSdogonium. 



The formation of the spore here does not differ from that of 

 (E. dioicmn, saving that there is no dehiscence^ apparently from 

 the union of the protoplasmic sac with the cell-wall at the micro- 

 pyle, which thus gives the latter a thickened margiuate appear- 

 ance ; and the vacuity above the spore being much less in extent, 

 which seems to prevent the spermatozoids from entering the 

 spore-cell previous to impregnation. The dehiscence of the 

 male cell for the escape of the spermatozoid is the same as that 

 in CE. dioicum. 



After the spermatozoid has been liberated, it remains for a 

 few moments, as in the former instance, to recover itself from 

 the shock of delivery, and then bounds away in among the rest 

 of the filaments ; but, curious enough, when it can be followed, 

 it is often found to return to the spore which has been developed 

 nearest itself. Here, alone or with others, it may make succes- 

 sive efforts at incorporation, until at last it becomes fixed by its 

 ciliated extremity to that part of the resting-spore which is close 

 to the micropyle (fig. 9). Its shape now becomes irregular, 

 indicative of the semi-fluid condition of its pellicle, and the exer- 

 tions it is making to squeeze itself through the micropyle, and 

 become incorporated with the resting-spore (fig. 10). This 

 stage only occupies a few moments, when it disappears, seem- 

 ingly by passing into the spore after the manner of a stone 

 falling into water ; but more probably the union is rather like 

 that of a drop of water with water ; for in the instance to which 

 I am alluding, no trace of it, or the opening caused by its entry, 

 could be subsequently detected in the resting-spore (fig. 11). 



The rest of the spermatozoids (for there is frequently a plu- 

 rality swarming round the micropyle) may continue their exer- 

 tions for an hour afterwards without effect, as was the case in 

 the instance under description (fig. 11), from which two infer- 

 ences already deduced derive corroboration, viz. that the sper- 

 matozoids in this species do not enter the spore-cell previous 

 to impregnation, as in (E. dioicum; and that the pellicle of the 

 resting-spore or of the remaining spermatozoids, or of both, had 

 become too hardened to yield to incorporation ; for the small- 

 ness of the spermatozoid compared with the resting-spore, and 

 the fact of a plurality existing round the latter, indicate that 

 more than one spermatozoid is required to complete the process. 



Sometimes a filament of this species appears without any 

 male cells, when the ordinary cells are longer and the resting- 

 spore-cells without any micropyle, although their contents have 

 assumed a spheroidal form. 



Observations. — I have but little to add by way of remark on 

 this mode of impregnation, further than that it seems to show 

 that the sporing of Spirogyra, &c., is of the same kind, and 



