from the Cell-contents of the Characeae. 11 



goiiidium equal in size to the one first mentioned. It may how- 

 ever yield a smaller one, and occasionally, in the same mul- 

 berry-group, may be seen gonidia of different sizes ; again, some- 

 times a whole group is composed of the same-sized gonidia, 

 which are not more than half the size of the common form, that 

 is l-8600th of an inch in diameter ; while occasionally a large 

 mass is seen creeping about which seems equal in size to the 

 whole of the gonidial substance of a large gonidial cell. Some- 

 times a compound mass of gonidia, composed of three or more 

 which appear to have flowed into each other, may be seen, with 

 their cilia projecting from different parts of the circumference. 



I have already alluded also to the variable contents of the 

 gonidia. In addition to the dull, bluish- green mucus, they also 

 frequently contain more or less of the bright refractive globules, 

 which, when the latter are beneath or in the midst of the mucus, 

 may be mistaken for the transparent vesicles which I shall pre- 

 sently mention. 



The gonidium may also contain more or less of the brown 

 matter, and occasionally, when it is unusually large and of a 

 Florence-flask shape, with the vesicle in front and a fragment of 

 brown matter of a bright colour present, it is hardly distin- 

 guishable from Astasia. 



Lastly, we come to the vesicles which are seen in the goni- 

 dium. While the gonidium retains its cilium and swimming 

 motion, the vesicle is for the most part single, and though 

 changeable in position with the movements of the cell-wall of 

 the gonidium, does not appear to be endowed with contractility 

 per se ; but when it loses its cilium and sinks down to the reptant, 

 polymorphic state, the vesicle becomes distinctly contractile, and 

 the gonidium is then hardly distinguishable from the young 

 Amoeba or sponge-cell. Frequently in this state also it presents 

 one or more hyaline vesicles which are not contractile, and only 

 change their position with those parts of the gonidium to which 

 they may be attached. 



We now come to the nucleus of the gonidial cell, and of this 

 I can state little more than has already been given. It is evi- 

 dent, that although the larger ones contain a nucleus, the smaller 

 ones do not, unless the irregular body fixed to their periphery 

 is to be considered its equivalent. I have mentioned that the 

 nucleus of the large cells appears to be the circular disk of the 

 mucus-layer, and that the latter is sometimes with and some- 

 times without its vesicle ; also that frequently, under an arrest of 

 development, it is surrounded by a crenulated membrane. The 

 fine granules of which the central part is composed, appear also 

 on these occasions to have become larger and more evident, and 

 in one instance they were replaced by three or four large glo- 



