ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
671 
of a free aerial mycele. Here and there bladders also are formed, and 
from these yellow masses are produced. The species of Achorion are 
parasitic on the horny layers of man and animals, whereon they form 
after a period the characteristic cups or scutulae. The nine species 
enumerated are: A. eutbythrix (F. griseus) ; A. atacton (F. sulfureus 
celerior); A. radians (F. sardiniensis) ; A. dicliroon (F. sulfureus 
tardus) ; A. alcromegalicum (F. scoticus) ; A. demergens (F . Batavus) ; 
A. cysticum (F. Hamburgensis) ; A. moniliforme (F. Bohemicus) ; 
A. larsiferon (F. Polonicus). 
The general differences of these species are then given in tabular 
form, after which are discussed their growth relations, and the classifi- 
cation founded thereon. The authors conclude their remarks by 
relating their cultivation and preparation methods, the results of which 
are massed together in tabular form. 
In most of their cultivation experiments the medium used was 
composed of 2 to 4 per cent, agar, 1/2 per cent common salt, 1 per cent, 
pepton, and 5 per cent, levulose. 
Mycetozoa. 
Hymenobolus, a new Genus of Myxomycetes.* — Under the name 
Hymenobolus parasiticus , Herr H. Zukal describes the type of a new 
genus of Myxomycetes belonging to the Perichsenacese, with the follow- 
ing diagnosis : — Sporangium singulare, regulariter circumlineatum, non 
pediculatum, fuligineum, minutum ; peridium simplex, sine incrustatione 
calcis ; capillitium in toto exigue formatum v. desideratum, lmvigatum, 
hyalinum ; sporidia majuscula, globosa, cum amplificato exosporio ab uno 
latere ; plasmodia miniata v. incarnata, in thallo lichenorum aliquorum 
parasitice sedentia, saepius in sclerotia, rarius in macrocystas v. micro- 
cystas mutantur. The sclerotes were first observed as bright red spots 
on lichens growing on a willow-tree. The young plasmodes creep along 
the bark of the tree till they reach the lichen, to which they attach 
themselves by the action of trophotropism, and on which they carry on 
a true parasitic existence, boring holes in the thallus often as far as the 
lower cortical layer. The plasmodes then become converted either into 
sclerotes or into megacysts and microcysts ; the ripe plasmodes expel 
their ingesta, and either become transformed into sporanges or move 
their position and then fructify. The parasitic habit, although it is 
only a facultative parasitism, distinguishes Hymenobolus from all the 
higher Myxomycetes. The pigment appears to be a lipochrome. 
Protophyta. 
a. Schizophycese. 
Scenedesmus. — Herr B. Franze f describes the structure of the 
membrane, chromatophores, and nucleus of Scenedesmus, especially of 
S. obiusus and acutus. The membrane has a very delicate rhomboidal 
areolation. Beneath this is a delicate layer of protoplasm, the granu- 
lations of which appear to form a continuous spiral ; and beneath this two 
* Oesterr. Bot. Zeitschr., xliii. (1893) pp. 73-7, 133-7 (1 pi.), 
f Beitr. z. Morph, d .Scenedesmus, 1892, 1 pi. See Bot. Centralbl., 1893, Beih.,p. 1G1. 
