ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 241 



elasticity of the cuticular layer and the looseness of the gonidiferous 

 layer. 



The author objects to the ordinary term " gonidial layer " as 

 applied to lichens, seeing there is no distinct layer composed entirely 

 of gonidia. The gonidia of Usnea articulata are of the form referred 

 by Bornet to Protococcus. In the older part of the thallus they are 

 perfectly free from hyphge, and are grouped in various ways in the 

 outer part of the gonidiferous layer ; but in the younger part of 

 the thallus the hyphse are composed of shorter cells and assume a 

 more contracted appearance, and the gonidia are often to be found 

 adhering to their apices. 



Algae. 



Symbiosis of Lower Animals with Plants.* — The relations which 

 subsist between the different organisms which live upon, or within 

 each other, are very various ; for the one, in its capacity of parasite 

 or companion or guest of the other, exercises on its host an influence 

 which is in some cases injurious, and in others advantageous to the 

 vital conditions of the latter. Many instances of this life in 

 common, or symbiosis, are known among animals as well as plants, 

 but the cases of symbiosis between animals and plants are less well 

 known ; and in regard to these, K. Brandt has made some interesting 

 communications to the Physiological Society of Berlin, of which the 

 following is an extract. 



Chlorophyll, which occiirs in all plants except the Fungi, is 

 known to occur in the animal kingdom also — in Ehizopoda, ciliate 

 Infusoria, fresh-water Sponges, the tentaculate Polypes, and many 

 marine and fresh-water Turbellaria. In all these the chlorophyll 

 is present in the form of sharply defined, oval, or round granules, 

 identical with its form in plants. Three contradictory views have 

 been held with regard to the presence in animals of chlorophyll: 

 (1) that the green particles are true chlorophyll-granules, (2) that 

 they are not produced by the animals themselves, but must be con- 

 sidered as parasites, (3) that in the case of the Protozoa, at any rate, 

 the green masses are merely parts of vegetable organisms which 

 have been absorbed after being submitted to digestion. Direct 

 observation has not yet decided the question. In his ' Natural 

 Conditions of Animal Existence,' Semper gives a critical sketch of 

 the investigations which have been made, and comes to the conclusion 

 that the green particles should be regarded either as endogenous 

 products of the animal, or as commensals, and he considers the latter 

 opinion the most probable one. The author has accordingly made ex- 

 periments with microchemical reagents in order to determine whether 

 the green bodies consist simply of chlorophyll combined with a 

 fundamental substance, or whether they contain colourless protoplasm 

 as well, and whether they have a nucleus, and are invested by a 

 cellulose membrane, also whether they are physiologically inde- 

 pendent, or continue to live after the death of the animals in which 



* Verhandl. Physiol. Ges. Berlin, 1881-2, p. 22. Cf. Naturforscher, xv. 

 (1882) pp. 15-17 ; and Rev. Internat. Sci. Biol., v. (1882) p. 149-52. 

 Ser. 2.— Vol. II. R 



