1876.] Botany. 173 
long been familiar to botanists; but it has been reserved for the well- 
known mycologist, Mr. Worthington G. Smith, of London, to discover 
quite recently the sexual mode of reproduction, which is quite analogous 
to that already known in other species of the same genus. On the 
mycelium, within the decaying tissues of the potato-plant, are produced 
the true sexual organs, the antheridia and odgonia, each of the latter 
containing a germinal cell or odsphere which is fertilized by a fecundat- 
ing tube put out by the antheridium, which discharges its contents into 
the protoplasm of the odsphere, thus converting the latter into an odspore 
or “resting spore.” The germination of this latter body has not yet 
been observed. The chief point of practical importance in this discovery 
is that it disposes of the theory which had been started of an “ alternation 
of generations,” namely, that the spores of the potato-fungus germinate on 
some other plant than the potato, producing a fungus which had not been 
recognized as identical with the Peronospora, the spores of this again 
producing the potato-fungus. The ground which has to be worked over 
for the destruction of the disease is thus considerably limited. — A. W. B. 
New Crassirication or Cryprocams.—In the last edition of 
his Lehrbuch der Botanik, Prof. J. Sachs proposes a new classifica- 
tion of the lowest section of cryptogams, which he distinguishes as 
Thallophytes, including the classes, hitherto considered distinct, of Alge, 
Fungi, Lichens, and Characew. He divides the section into four classes, 
each consisting of two parallel series, the one containing chlorophyll and 
commonly known as Algæ (including Characee) ; the other destitute of 
chlorophyll and commonly known as Fungi (including Lichens). The 
classes are as follows: Class 1. Proropuyta. This class comprises 
the simplest known forms of vegetable life, unicellular, or the cells con- 
hected into filaments, rarely into more complicated tissues; no mode of 
sexual reproduction is known. To the chlorophyll-containing series be- 
long the Chroococcacee, Nostocacea, Oscillatoriee, Rivulariee, Scyton- 
“mee, and the Palmellacee (in part) ; to that destitute of chlorophyll the - 
Schigomycetes (bacteria) and Saccharomyces (yeast). Class 2. Tyeo- 
SPORE Asexual propagation various; sexual propagation by means 
of 8Ysgospores, the result of a process of conjugation. This is divided 
into two sections. In the first the conjugating cells are locomotive, as in 
the Volwocinee an d Hydrodictyee (containing chlorophyll), and the 
Myomycetes (destitute of chlorophyll) ; the second section includes the forms 
m which the conjugating cells ate stationary, namely, in the first series 
> Conjugate (comprising the Mesocarpee, Tyguernee, Desundiee, and 
‘atomacee) ; in the second series the 7% ‘ygomycetes (comprising the Mu- 
corim and Piptocephalide). Class 3. OdsrorE®. Reproduction by 
oogonia, containing an oösphere or embryonic cell, becoming an oöspore 
o resting-spore by the act of impregnation. In the series containing 
chlorophyll are Spheroplea, Vaucheria, the Oedogonee, and Fucacee ; 
' the series destitute of chlorophyll the Saproleginee and Peronosporee. 
