Notes on the Morphology of the Fucacete. 37 



1. The parasitic habit of the plant. Up to the present time but 

 few truly parasitic Algse have been recorded. Notheia anomola grows 

 vigorously on Hormosira and Fucodium. 



A longitudinal section of the junction of the Notheia and Hormosira, 

 when stained with methylene blue, shows that the cells of the thallus 

 of Hormosira stain a deep blue, as also do the outer layers of cells 

 of Notheia, but that the central cells of Notheia, and a wedge-shaped mass 

 of tissue, which penetrates the thallus of the host, remain unstained. The 

 appearance of the cell-contents and the cell-walls in the neighbourhood of 

 the wedge is suggestive of tissue in a state of degeneration ; but it is im- 

 possible to say anything decisive on this point unless fresh tissues are 

 examined. 



2. The production of the lateral branches. Each branch rises from 

 the base of a conceptacle, even though this be filled with hairs and 

 reproductive organs. 



3. The presence of one kind of sexual reproductive organ. The 

 reproductive organs are developed in well-formed conceptacles. In the 

 latter, hairs are present at a very young stage ; they appear to grow 

 only from the base at first, and stand up parallel to one another and 

 perpendicularly to the base ; other hairs appear later, growing from the 

 sides, among which the reproductive organs are developed. 



The reproductive organs have every appearance of oogonia, but no 

 antheridia have ever been recorded, and I have examined many plants 

 for them in vain. The accounts of the number of the oospheres have 

 differed in various records, but I have invariably found eight present, 

 generally arranged in the same manner, that is, one oosphere at either 

 end of the oogonium, the remaining six in the centre in two groups of 

 three oospheres each. MARGARET O. MITCHELL. 



EXPLANATION OF PLATE XI. 



Fig. i. Male conceptacle of Xiphophora Billardierii Mont, (x 66). 



Fig. 2. Antheridia ( x 375). 



Fig. 3. Female conceptacle ( x 66). 



Fig. 4. Oogonium ( x 190). 



Fig. 5. Notheia growing on Hormosira (a), and Fucodium (b}. Nat. size. 



Fig. 6. Diagrammatic section of the thallus to show the origin of a lateral 



branch from a conceptacle containing oogonia ( x 250). 

 Fig. 7. ,, Oogonium ( x 250). 



Fig, 8. Section of the junction of Hormosira and Notheia : the cells with 



darker contents represent those stained with methylene blue ; 



the other cells are unstained ( x 250). 



r 



