ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
207 
gelatinous substance secreted by themselves. This adhesion may,, 
however, be due to artificial conditions. The spherical spores, which 
are described in detail, rest unchanged for a week and apparently da 
not copulate. They then thrust out a process wdiich elongates, and 
division of nucleus and chromoplast takes place, followed by cell 
division. Further growth is described, up to a protonema-like filament 
with the initial cell at one end. The cells of the filament increase in 
size and in number, and in the third week a hyaline hair arises from 
the initial cell. In the fourth week the filament consists generally of 
ten to twelve cells, one of which (sometimes more) increases enormously 
in size, the chromoplast gradually decomposes and the cell is filled with 
minute hyaline granules lying in mucilage. These develop into 
spermatozoids, the formation and discharge of which are described. 
The cells which produce oogonia may be recognized by the unusually 
intense colour of the chromoplasts, w r hich contain a rich granular 
substance. The periclinal surface bulges out towards one side, becomes- 
septated at the base, rounds itself off, and becomes detached as a free 
oospore, about 10 ^ in diameter. The process of fertilization was not 
observed. The oospores rest for a very short period, germinating 
within a few days of detachment from the mother-cells. Their develop- 
ment was only followed till they formed three-celled filaments, which 
took place at the end of the fifth week. The author suggests that the- 
csespitose habit of P. Fascia may be due to the aggregations of the 
oospores and not of the zoospores. He regards the swarmspores as 
asexual, and therefore, in the life-history of Phyllitis, a gametophyte 
generation follows the sporophyte. What becomes of the sporeling 
germinated from the oogonium, during the half-year until the appear- 
ance of the well-known form of P. Fascia in late autumn, is not 
known. E. S. G. 
Researches on the Variation of Iodine in the Principal Laminarias 
of the Breton Coast. — P. Freundler and Y. Menager ( Office Sci. et 
Techn. Peches Maritime ® , Paris : Notes et Memoires , No. 13, 1922, 
24 pp.). A continuation of the report on the economic use of Laminaria , 
published as No. 5 of these memoirs. The following results have been 
obtained. No Laminaria survives beyond the winter if the frond has 
been injured ; consequently, collection of material by cutting was 
discontinued during last year. The tearing off of plants in collecting 
prevents or hinders the attachment and development of young plants. 
Intensive exploitation by boats causes a diminution in the size and 
number of the algae, although it does not cause all the serious damage 
imputed to it. The mode of collecting should be methodical and 
discontinuous. The method of determining the quantity of iodine has 
been improved, and can be accurately stated within an error of 2 p.c. 
The results obtained are : — 1. A general diminution of the amount of 
iodine during desiccation. 2. The variation of this amount under the 
influence of season, region, and age. 3. The order of magnitude of 
these variations in the different parts of the alga, in the same species. 
It is proposed, in the year 1922, to carry out (1) more extended visits 
of inspection, with the object of determining the conditions of periodicity 
