AND GERMINATION OF ALG^. C7 



and the true thick cellulose membrane, is a very thin layer of 

 colourless substance which I have elsewhere described as the 

 " cutaneous layer" (Hautschicht) of the cell-contents.* The 

 sporangium is also especially characterized by the circum- 

 stance that a considerable number of oil-drops accumulate in 

 it and apparently occupy the whole of its proper cavity. 



At this stage of development, a septum is suddenly formed 

 at the base of the sporangium, which is henceforth an inde- 

 pendent cell, completely separated from the parent tube 

 (fig. 4). Even before the sporangium has become separated 

 from the parent tube by the septum, there may be noticed in 

 the rostrate elongation directed towards the " hornlet," the 

 gradual accumulation of a colourless fine granular substance, 

 of the same nature as that with which the wall of the parent 

 tube and of the sporangium is lined on the inner surface, and 

 which, as I have already stated, has been termed by me the 

 cutaneous layer. T'his accumulation of the " cutaneous layer" 

 in the fore part of the rostrate process is continued after the 

 formation of the septum between the sporangium and tube, 

 and in consequence of its continued increase the remaining con- 

 tents of the sp07-angium, the oil-drops, chlorophyll, and plasma 

 are by degrees pushed towards the back and base of the 

 sporangium (fig. 4). Whilst these phenomena are being ma- 

 nifested in the sporartgium, the " hornlet" also undergoes very 

 remarkable changes. In its apex, which, so long as the hornlet 

 continues to grow, presents the same conditions as the summits 

 of the growing branches of Vauclieria, the contents, owing 

 to the disappearance of the chlorophyll, have become almost 

 completely colourless, except that occasionally a few chloro- 

 phyll granules remain ; sometimes more sometimes less. 

 Thus the point of the " hornlet," like that of the sporangium, 

 appears at this time to be filled with a colourless substance, 

 but which is not constituted by an accumulation of the 

 " cutaneous layer" at this point, but manifestly arises from a 

 molecular change associated with an alteration of form and 

 colour in the contents previously existing at the apex. This 

 difference in the mode of formation of the colourless substance, 

 occupying the apices of the horn and of the sjiorangium, 

 should be carefully borne in mind ; it is very essentially con- 

 nected with the different morphological destination of the 

 two substances. So soon as the contents of the point of the 

 " hornlet" have become colourless in the mode just described, 

 they appear to be constituted of a very fine-grained granulosa 



* A notice of the Author's ' Researches on the Structin-e and Formation 

 of the Vegetable Cell,' will appear in the next Number of the ' Quarterly 

 Journal of Microscopical Science.' 



F 2 



