140 Grubb .— The Attachments of Porphyra umbilicalis. 
6 . Modifications in the disc filaments are shown to take place very 
early in the life of the sporeling. 
7. Porphyra grows usually on a substratum of rock, but in plants 
occurring on breakwaters the filaments are shown to have the power of 
penetrating the dead woody tissue. Porphyra has hitherto very rarely been 
found epiphytic, and never parasitic, but in two plants found on Fucus 
serratus the disc filaments had penetrated the living cells of the host. This 
seems to indicate the capacity for either epiphytism or parasitism if once 
secure contact is obtained. 
Westfield College, 
London, 
July, 1922. 
References. 
1. Berthold, G. : Die Bangiaceen des Golfes von Neapel. Fauna u. Flora des Golfes von Neapel. 
Mon. vii, 1882. 
2 . Borgesen, F. : Algal Vegetation of the Faerdese Coasts, 1905, p. S30. 
3 . Cotton, A. D.: Clare Island Survey. Part XV: Marine Algae. Proc. Roy. Irish Academy, 
vol. xxxi, p. 30. 
4 . Delf, E. M.: Attaching Discs of the Ulvaceae. Ann. Bot., xxvi, No. 102, 1912, p. 403. 
5 . Derick, C. M. : Notes on the Development of the Ploldfasts in certain Florideae. Bot. Gaz., 
Oct. 1899, p. 264. 
6. Harvey : Phycologia Britannica. Vol. iii, Rhodophyceae, i. 
7 . Hus, H. T. A. : Account of the Species of Porphyra found on the Pacific Coast of N. America. 
Proc. Californian Acad. Sc., 3rd ser., vol. ii, 6, 1902, p. 173. 
8 . Tobler-Wolff, G.: Zur Biologie von Polysiphonia fastigiata . Beihefte z. Bot. Centralbl., 
Bd. xxiv, 2. Abt., 1909, p. 113. 
9 . Thuret et Bornet : Etudes Phycologiques, 1878. 
EXPLANATION OF PLATE I. 
Illustrating Miss Grubb’s paper on the Attachments of the British Species of Porphyra. 
All figures drawn with a No. 3 eyepiece (Swift) and D.D. objective (Zeiss), except Fig. 2, which 
was drawn with a No. 3 eyepiece and A.A. objective (Zeiss), and Fig. 1, which was drawn with 
a No. 4 compens. ocular (Zeiss) and a apochromatic objective (Swift). 
Fig. 1. Apex of a typical disc filament with nuclei (^ apochromatic). 
Fig. 2. Young sporeling. x 250. 
Fig. 3. Transverse section of swollen tips of disk filaments (stippled) in tissues of the wood, 
x 750. 
Fig. 4. Transverse section of a group of cells formed from the apex of a disc filament in the 
wood of the post, x 750. 
Fig. 5. Filaments from the base of the disc of Porphyra boring into the tissues of Fucus 
serratus. x 750. 
