SUMMARY OF CURRENT RESEARCHES RELATING TO 
662 
Abnormal Diatoms. — Dr. P. Miquel * records the occurrence, in a 
series of cultures of Nitzschia linearis , of a number of abnormal forms 
which he believes to be du3 to unfavourable conditions of heat, light, 
or nutriment, or to the presence of injurious chemical substances in 
the medium. 
Mr. S. Lockwood f affirms, as the result of observations made through 
a long series of years, that if kept in darkness, the spores or germs of 
diatoms may retain their vitality for a period of sixteen years. When 
germinating after that length of time, they may give rise to remarkable 
anomalous forms. 
White Forms of Euglena.l — E. Couvreur has studied the gradual 
disappearance of chlorophyll-grains in Euglena and the resulting white 
forms. These can live for some time at the expense of the reserves of 
paramylon, but they are incapable of multiplying. There is no doubt, 
he concludes, that they are Algae, not Protozoa. 
/3. ScRizomycetes. 
Action of the Rontgen Rays on Bacteria.§— Contrary to the ex- 
perience of Wolfender and Forbes-Ross, Herr H. Rieder finds that the 
Rontgen rays have a greater inhibitive or even destructive effect on 
bacteria than those of ordinary light. This was found to be the case 
with B. coli, Staphylococcus pyogenes aureus , Streptococcus pyogenes , the 
bacilli of cholera, diphtheria, typhus, and fowl-cholera. Bacteria sus- 
pended in agar, blood-serum, or gelatin plates, perished in an hour under 
the action of the Rontgen rays ; even bouillon cultures of the cholera 
bacillus were killed by long exposure. 
Nucleo-proteids of Bacteria.|] — The question of immunity and of 
toxins and anti-toxins is closely associated with that of the chemical 
composition of the micro-organisms themselves. The previous researches 
of Sig. G. Galeotti indicated that the proteid substance they contain is 
nucleo-proteid. The bacterium specially investigated during the pre- 
sent research was Ernst’s Bacillus ranicidus, large cultures of which 
are obtainable. The neclec-proteid separated from this by the usual 
methods yielded xanthine bases. It contained a low percentage of 
nitrogen (12), while the phosphorus amounted to 1*01 to 1*8 per 
cent. It produced intra-vascular coagulation in rabbits, but small doses 
conferred immunity. The colour reactions with anilin dyes are also 
dealt with. 
Denitrifying Micro-organisms.^]' — Herr 0 . Kiinnemann finds that 
horse-dung contains two kinds of denitrifying organisms, of which one, 
B. denitrijicans i, is effective only in symbiosis with B. coli. The other 
is a variety of B. denitrijicans ii. The same micro-organisms were some- 
times, but not always, found in cattle-dung. The loss of nitrates may 
* Ann. de Micrographie, x. (1898) pp. 177-81 (2 figs.), f Tom. cit.„ pp. 1-9. 
X Ann. Soc. Linn. Lyon, xliv. (1898) pp. 99-100. 
§ Miinchener Med. Wochenschr., 1898, No. 4. See Bot. Centralbh, 1898, Beih., 
p. 4. Cf. thia Journal, ante , p. 460. 
|| Zeit. Physiol. Chem., xxv. (1898) pp. 48-63. See Joum. Chem. Soc., lxxiii. 
and lxxiv. (1898) Abstr., pt. ii. p. 444. 
f Landw. Versucbs-Stat., 1. (1898) pp. 65-113. See Journ. Chem. Soc., lxxiii. 
and lxxiv. (1898; Abstr , pt. ii. pp. 444-5. 
