en 
10. Mesogloia vermiculata, Le Jol. 
This plant is a summer annual of limited occurrence. 
It first appears in June as minute plants in well-sheltered 
localities and grows with great rapidity achieving an 
increase of a few inches in as many weeks. Plants 
collected in July, 6-8 inches in length, were plentifully 
provided with unilocular sporangia. Towards the end 
of August the plants are readily detached from their hold 
and washed away. They have almost entirely dis- 
appeared from the littoral zone by the middle of September. 
Cultural experiments have shewn that the zoids emerging 
from the unilocular sporangia (haploid) germinate very 
slowly into minute ectocarpoid filaments bearing 
plurilocular sporangia. These plants are haploid and 
serve the function of gametophytes since the zoids from 
their sporangia fuse in pairs. The union of two similar 
gametes results in a zygote which germinates into a 
cellular disc completely adherent to the substratum. Up 
to the present the discs have shewn only the beginnings 
of upright filaments that will doubtless eventually develop 
into the macroscopic Mesogloia plants and so complete 
the life-cycle. Mesogloia thus falls into line with the 
life-cycle of Laminaria in possessing a macroscopic 
asexual phase and a microscopic gametophyte phase. It 
differs from Laminaria in that the macroscopic phase is 
restricted to the summmer season while the minute 
phase alone represents the species during the winter. 
11. LEvythrocladia subintegra, Rosenv. 
This plant forms minute discs adherent to the walls of 
Polysiphonia spinulosa var. major which was found as an 
epiphyte on Desmarestia aculeata dredged from deep water 
outside Port Erin Bay. The specimens have been 
examined and identified by Professor Rosenvinge and a 
description will be found in his papers on the Marine 
Algae of Denmark, Part I, p. 73. 
H 
