80 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Mycetozoa. 
Plasmodiophora Vitis and californica.* * * § — MM. P. Viala and C. 
Sauvageau describe in further detail the diseases of the vine known as 
“ brunissure ” and the Californian disease caused respectively by Plasmo- 
diophora Vitis and californica. The latter is exceedingly destructive to 
both the wild and the cultivated vines in California, but is at present 
unknown in Europe. The relationship of these organisms to allied 
species is discussed in detail. 
Protophyta. 
a. Schizophyceae. 
Biology of Diatoms. - )* — L’Abbe Count F. Castracane describes a 
form of moist chamber or live-box, which he has found peculiarly well 
adapted for following out the life-history of individual diatoms. His 
observations under these conditions confirm him in the view that diatoms 
during the early stages of their existence remain fixed to one spot; and 
that the usual mode of their propagation is by spores or gonids. 
In another paper J the same author reviews the opinions of the 
various authorities, and the arguments in favour of the existence of a 
mode of propagation by means of spores. He further states his con- 
viction that, even in this embryonic stage, diatoms are enclosed in a 
more or less silicified envelope. The remains of these envelopes are 
sometimes to be found in the form of minute siliceous agglomerations 
within the parent frustule. No trace remains of the sporangial sac 
within which these embryonic forms were enclosed. 
Species of Diatoms. § — Dr. A. M. Edwards doubts the existence of 
true species, or even genera, among the Diatomacese. At all events, he 
claims to have established that all the various species of Schizonema 
and Homoeocladia are but forms of two species, while both these genera 
must be united with Nitzschia. Again, there are no good characters to 
distinguish Schizonema from Navicula ; and the twenty-four species of 
Micromega can all be grouped under Navicula foetida. Dr. Edwards’s 
arguments are based on the fact that he finds specimens of the alleged 
different species or genera “ in the same tube.” 
Schmidt’s Atlas der Diatomeenkunde. — The last part published of 
this magnificent work (Heft 45) consists of 4 pis., 177-180 ; it is almost 
entirely occupied with species and forms of Melosira , fossil and recent, 
also a few of Skeletonema and Trochosira. 
B. Schizomycetes. 
Influence of Light on Bacteria. || — Prof. H. Buchner, who recently 
showed the germicidal influence of light on bacteria suspendei in water, 
has now demonstrated its fatal action on cultivations of bacteria on 
solid media. Alkaline meat-pepton-agar is liquefied by boiling, and 
* Journ. de Bot. (Morot) vi. (1892) pp. 355-63, 378-88 (1 pi.). Cf. this Journal, 
1892, p. 836. 
t La Nuova Notarise, iii. (1892) pp 146-51. Cf. this Journal, 1892, p. 655. 
+ Mem. Pontif. Accad. Nuovi Lincei, 1892, 31 pp. 
§ Amer. Mon. Micr. Journ., xiii. (1892) pp. 212-6. 
[| Centralbl. f. Bakteriol. u. Parasitenk., xii. (1892) pp. 217-9 (1 fig.). 
