ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 387 



Pylaiella Postelsias.* ('. Skottsberg describes a new type in the 



genus Pylaiella which he calls P. Postelsise, and places it in a nev. sub- 

 genus Panthocarpus. The alga in question forms dark brown tufts 

 5-10 mm. long on the stems and leaves of Postelsia palmseformis. The 



tufts are sometimes very dense and cover only a very small area ; some- 

 times, especially on the stems of the host, they form larger patches of a 

 short velvety indument. They consist of innumerable simple or sparely- 

 branched filaments, monosiphonous while sterile. The basal part is 

 formed by branching densely interwoven filaments, creeping mi the 

 surface of the host or penetrating between the cortical cells. In the 

 system of erect filaments there is a distinct difference between long and 

 short branches, and these are described in detail. There is one genera- 

 tion of long and one of short branches, which gives to this alga a very 

 characteristic appearance. No hairs have been found. Only pluri- 

 locular sporangia are known. The author discusses the systematic 

 position of P. Postelsise, which represents a rather primitive type among 

 the Ectocarpacea'. 



Saccorhiza bulbosa. f — C. Sauvageau has made a study of the 

 development and biology of Saccorhiza bulbosa, and his paper on the 

 subject is the first complete account that has ever been published of 

 the life-history of a Laminaria from germination to the adult plant. 

 Certain authors have studied the germination and concluded that the 

 erect plants arose from some sort of protonema. The author states at 

 once that this is an error, and that no protonema intervenes in the 

 normal plant ; the thallus arises direct from the germinating spore. 

 Experiments were carried out in cell-cultures, in glass dishes, and on 

 the sori of the plant itself. All the results agreed. The process of 

 germination of the zoospore is described in detail. Some spores show 

 two red spots and two nuclei, but this is mei^ly the result of incomplete 

 segmentation of the protoplasm and not of conjugation. In some rare 

 cases where growth is slow and weakly, germination of the spore pro- 

 duces a creeping filament which bears one or more upright branches 

 and, at the summit, a small Laminaria. The author considers that 

 these abnormal growths have probably given rise to the protonema 

 theory. The different stages of growth of the lamina and the bulbous 

 base are described. The oldest individuals reach their maximum growth 

 (about 3 m. in the Gulf of Gascony) in July. The younger ones con- 

 tinue to grow till towards the end of the summer, when they stop growth, 

 leaving the stipes of the youngest ones very short. Then begins the 

 fructification. Many individuals, however, disappear without fruiting, 

 at any rate on their upright thallus. Since the time of Reaumur (171 :' 

 authors have regarded the frilled marginal wings of the stipes - 

 characteristic of S. bulbosa, and since Sowerby (1807) these have been 

 regarded as the principal seat of fructification. In the Gulf of Gascony 

 plants the wings are wanting, and the sori are spread over the lamina, 

 less generally on the stipes and never on the margins. This curious 

 variation increases the affinity between S. bulbosa and Phyllaria. By 



* Univ. California Publ. (Bot.) vi. (1915) pp. 153-64 (3 pis.). 

 t Ccmptes Rendus, olx. (1915) pp. 445-8. 



