690 r SUMMARY OF CURRENT RESEARCHES RELATING TO 



Observations were made as to the rate of growth and the time occu- 

 pied in the formation of the rosettes, by inoculating from rosette-free 

 potato cultures into a hanging-drop of broth and observing micro- 

 scopically. For the first two hours after inoculation no rosette formation 

 was noted, but from this time onwards up to 24 hours the rosettes 

 increased in numbers, reaching their maximum at the last-named point, 

 the time required for the appearance of the rosettes corresponding ap- 

 parently to that required for cell-multiplication to take place. The 

 author is of opinion that the formation of the rosettes is too regular 

 and perfect to be explained as a passive agglomeration caused by some 

 agglutinating substance, whilst observations upon cell-division under 

 conditions unfavourable to the bacillus, e.g. pressure and lack of oxygen, 

 still showed the tendency of the dividing cells to form rosette groups, a 

 fact which strongly supports the theory that the phenomenon must be 

 closely connected with the vital processes. 



Intestinal Bacteria of Chironomus Larvae.* — Leger, during the 

 course of some researches upon the parasitology of the Diptera, ob- 

 served three micro-organisms present in the intestinal canal of the 

 larvae of Chironomus plumosus, with such constancy as to constitute them 

 true parasites. These three bacteria were, in order of frequency, a 

 streptothrix, a bacillus, and a spirillum or spirochaeta. 



The streptothrix occurred as hyaline filaments, 1*5 /a long, forming 

 bundles or interlacing tresses, also ovoid conidia, 2 • 8 p in length, in 

 the posterior, and, but rarely, in the middle intestine. Occasionally it 

 is present in such masses in the rectum as to lead to great distension. 



The bacillus was less frequently observed than the streptothrix, 

 although sometimes the two organisms were associated ; it was a short, 

 straight, or slightly curved motile rod, 6 to 8 fi in length, sometimes 

 free in the intestinal canal, but usually attached by one extremity to the 

 surface of the epithelial cells. It forms ovoid spores, 1 ■ 7 fx long, at the 

 free extremity, which becomes somewhat swollen. 



The third organism, the spirillum, rarer than either of the above- 

 mentioned species, closely resembles the Spirillum Obermeyerei. It 

 occurs as long filiform threads, 15 to 20 /x in length, and containing in 

 such a length four or five very pronounced curves. Like the bacillus, it 

 is attached by one extremity to the intestinal wall, the unattached por- 

 tion exhibiting constant rapid undulatory movements. The author 

 concludes that these spirochsetsB are the structures that previous ob- 

 servers (e.g. P. Vignon) have described as the cilia of the epithelial cells 

 of the intestine. 



Bacillus Lacto-rubifaciens.f — Gruber isolated a bacillus from milk, 

 which produces a red coloration of that fluid, and possesses the following 

 characters. It is a short rod with parallel sides and rounded ends, 

 occurring singly, in pairs, and short threads, 1 • 75 /x to 14 fx long, by 

 • 4 fx to • 6 fx. Occasionally diplo-bacilli are found, and sometimes more 

 or less oval single rods, many of the rods showing distinctly refractile 

 granules, and from old cultivations the stained preparations show dis- 

 tinct central granules, which are not, however, true spores. The or- 

 ganism is motile, with peritrichous flagella. The bacillus grows well 



* Comptcs Rendu?, exxxiv. (1902) pp. 1317-9. 



t Ccntralbl. Bakt., 2 ,e Abt., viii. (1902) pp. 457-62. 



