ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 483 



development of tlie part which usually constitutes the foot. The 

 peculiarity does not appear to be the result of the attacks of insects 

 or other parasites. 



Hepaticae inclosed in Amber.* — Dr. K. M. Gottsche sums up 

 what is at present known with regard to the remains of Hepaticae 

 which have been found inclosed in amber. He refers them to the five 

 following genera, viz. — Frullania, Lejeunia, Badula, Scapania, and 

 Jungermannia. 



Algee. 



Evolution of Algae.t — MM. E. Heckel and J. Chareyre trace the 

 probable evolution of the various groups of algse from the simplest 

 forms (chlorophyllaceous Protophyta), such as Protococcus, from 

 which spring at once three parallel series distinguished by the colour 

 of their endochrome, green, blue-green, and brown. Although this 

 difference has, in itself, but little physiological value, being depen- 

 dent on adaptation to external conditions as respects light, it never- 

 theless serves as the point of departure of three distinct lines of 

 descent. Of these the blue-green series never advances more than a 

 few steps in development, the brown series attains a considerably 

 higher degree of differentiation, while the green series developes into 

 a far larger number of very distinct forms, finally giving birth to 

 the Florideae and Muscinese. 



The green series of algge derived from Protococcus divides at 

 once into four parallel groups, the Siphoneae, CoenobieaB, Confervacese, 

 and Conjugatee. In the Siphonea3 the single cell branches, and the 

 different portions assume different functions; in the Coenobieag a 

 number of intercellular organisms collect into a colony; in the 

 Conjugatae and lower Confervaceae the primitive cell divides into a 

 multicellular filament ; in the higher Confervaceae into a plate or 

 mass of cells. 



The group of Siplioneae starts from the Sciadieae, in which the 

 conjugation of zoospores presents the first manifestation of sexuality. 

 In the Bryopsideae (Bryopsis, Caulerpa, Acetahularia, &c.), the 

 thallus displays great ramification, and this family then gives birth 

 to two branches, the Codieae with isogamous reproduction, and the 

 Vaucherieae in which the sexual elements are differentiated into 

 oospheres and antherozoids. 



The Ccenobieae start from the isogamous Hydrodictyese, the next 

 stage being the Volvocineae, at the base of which are isogamous types 

 like Pandorina, advancing to others like Chlamydomonas in which the 

 sexual elements differ only in size, closing with the higher Volvo- 

 cineae, like Volvox and Eudorina, in which heterogamy is displayed 

 in the differentiation of antherozoids and oospheres. 



The Conjugatae are all filamentous algae, commencing with the 

 isogamous Desmidieae in which septation is only rudimentary, 



* SB. Gesell. Bot. Hamburg, Oct. 30, 1884. See Bot. Centralbl., xxv. 

 (1886) p. 95. 



t Journ. de Micrographie, ix. (1885) pp. 452-8, 508-10. 



