ZOOLOGY AND BOTANY, MICEOSCOPV', ETC. 321 



individuals of mediocre dimensions are united together in great numbers. 

 The anatomical structure points to the inclusion of the species in Litho- 

 thamnium, in which its nearest ally is L. compactum Kjellm., which has 

 both crustaceous and branching forms. The author proposes to name 

 the present Post-pliocene form, f . ramulosa. It is nearer to f . ti/pica than 

 to the other forms. The author discusses the distribution of L. com- 

 pactwn, which is a northerly one, and puts forward possible explanations 

 for its occurrence at Brindisi in Post-pliocene times. 



Saccorhiza bulbosa.* — C. Sauvageau writes on the annual periodicity 

 of Saccorhiza bulbosa, in contrast to other Laminarias which are perennial. 

 He has followed its life-history at Guethary (Basses-Pyrenees) during 

 several years, and finds the evidence indisputable. S. bulbosa attains 

 its greatest size in July ; then gradually diminishes owing to wear and 

 tear and probable cessation of growth. The fructification appears in 

 August, but is rare. In October many plants are fertile on the stipes 

 and the frond, dispersing a prodigious number of zoospores. All the 

 divisions of the frond are cropped short and truncated, in large as well 

 as poorly-developed plants, fertile as well as sterile. This is apparently 

 a seasonal phenomenon, and is aided by the attacks of Helcion pellucidum. 

 Towards the end of the autumn the plant is reduced to its bulb, which 

 up to then has been sterile. In February or the beginning of March 

 the bulbs are often fertile, though more or less damaged. In April 

 they entirely disappear. The first plantlets appear in the second fort- 

 night of February ; the others in March and April. All grow rapidly, 

 and one finds no more till the following year. Thus the entire develop- 

 ment of *S'. bulbosa is accomplished in a few months. The plantlets 

 are found during three months only, while the emission of zoospores 

 lasts for seven consecutive months. The young April plants arise from 

 zoospores recently emitted from the bulbs, not from old prothallia or 

 resting embryospores ; and the origin of the February plantlets is the 

 same. Consequently, the sori on the bulbs suffice to reproduce the 

 plant, and the spores which were formed during the autumn do not 

 germinate in the open, though they germinate successfully under 

 culture. Some adverse factor in nature prevents germination from the 

 middle of the summer to the beginning of winter. The author discusses 

 what this may be, but comes to no conclusion. In other localities he 

 has found plants in all stages of development, notably at Rivadeo in 

 October and at La Corogne at the beginning of November. The 

 author describes the luxuriant growth of S. bulbosa both in size and 

 extent at Roscoff, and the distinct impression of the gradual disappearance 

 in September of the old specimens. Plants of all ages, however, may be 

 found at other times of the year. At Roscoff the annual character of 

 S. bulbosa is very clearly shown. 



Plantlets of Laminaria.t — C. Sauvageau describes the development 

 of the young plants of Laminar la Jiexkaulls and L. saccharina. In a 

 former paper he described the developmental stages of plantlets of 



* Comptes Rendus, clxiii. (1916) pp. 396-8. 



t Comptes Rendus, clxiii. (1916) pp. 522-4 (figs.). 



