ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
225 
respect, except that they contain a blue-green phycochrome, and which 
seem to present a connecting link between Spirochsete and Spirulina. 
The filaments are of a corkscrew form, and were in very active motion, 
probably from the possession of terminal cilia at both ends. 
Conjugation in Diatomacese.* — Mr. T. H. Buffham describes a case 
of conjugation in Orthoneis binotata. The entire gelatinous investment of 
the diatom is termed by him the perigloea, and certain long processes 
which pass through mammiform protuberances of the perigloea at the 
extremities of the minor axis tentaculoids. In the present species these 
reach a length of 320 /x. It is only the smallest individuals which 
manifest conjugation. A frustule which has completed, or almost 
reached, the stage of self-division, has a bulbous addition to the upper 
part of its perigloea, into which the double frustule rises. The endo- 
chrome then passes out of the lower, which may be considered the male, 
into the upper or female frustule, The upper frustule then divides, and 
forms two masses of endochrome, which develope into two sporangial 
frustules of exactly double the length and width of the parent. One 
valve of the mother-frustule is closely applied to the upper side of the 
upper sporangial frustule, and the other valve to the lower side of the 
lower frustule. 
The author also confirms his previous observations on the conjugation 
of Mhabdonema arcuatum. 
Index to the Photographs of Moller’s Preparations of Diatoms.f — 
Herr J. D. Moller publishes an index of the species delineated in his 
photographic plates of diatom-preparations. He maintains that most 
species of diatom vary greatly, and pass over into one another in various 
directions in the most confusing manner. 
13. Schizomycetes. 
Development of Bacteria at Low Temperatures.^ — Prof. J. Forster, 
in the course of some remarks on the viability of Bacteria at low tem- 
peratures, shows that the dictum of Migula, though true as a rule, cannot 
be accepted as a law. Migula stated that the increase of water-germs 
only took place when the temperature was some degrees above zero. In 
the course of the past year the author, in co-operation with Herr S. 
Bleekrode, has made numerous experiments in order to ascertain if 
bacteria were capable of development at the temperature of melting ice. 
For this purpose bacteria of sea-water, fresh water, food-stuffs, road- 
sweepings, and refuse were cultivated in Koch’s gelatin, and then on 
plates. Instead of an incubator a refrigerator was used. In this the 
plates were kept for over a week, at a temperature of. 0°. After 10-12 
days the material was examined by transference to Loeffler’s bouillon, 
gelatin, &c., some samples being refrigerated, some incubated at 37° '5. 
The results of these experiments showed that only a few kinds of 
bacteria were able to grow at 0° : yet there were numerous individuals 
of the kinds found in our daily surroundings, e. g. in food-stuffs, 
* Journ. Quek. Micr. Club, v. (1892) pp. 27-30 (1 pi.). 
f ‘ Yerzeichniss d. in d. Lichtdrucktafeln Mollerschen Diatomaceen-Praparate 
enthaltenen Arten,’ Wedel, 1892, x. and 176 pp. 
X Centralbl. f. Bakteriol. u. Parasitenk., xii. (1892) pp. 431-6. 
