TRANSACTIONS OF SECTION D. 681 



are found amongst the Heliozoa. Tlie protoplasmic nature of the pseudopodia is 

 inferred from the following facts : — 



They are destroyed by nitric acid and by a low red heat; they give no cellulose 

 reaction with Schultze's solution or with iodine and sulphuric acid ; they stain 

 readily with Kleinenberg's hsematoxyliu ; they also stain with borax carmine, 

 picro-nigrosin and alcoholic saftranin. Pseudopodia similar in shape are found 

 amongst the Heliozoa generally, but pseudopodia agreeing with these in the 

 minutest details are found on some specimens of Archerina lioltoni, a Heliozooia 

 which occurred in vast numbers with the diatoms in London. Other as yet un- 

 determined Heliozoa occurring in the same water have verj' similar pseudopodia. 



3. On Nuclear Structure in the Bacteria. By Harold Wagee. 



Owing to the small size of the cells in the bacteria, the presence of a nucleus, 

 or of anything akin to nuclear structure in them, has not yet been satisfactorily 

 demonstrated. Dr. P. Ernst, has, however, described certain bodies which to him 

 appeared to be of the nature of nuclei, inasmuch as they possessed a reaction 

 towards reagents diflerent from that observed in spores. 



It is interesting to note that in the closely allied group of the Cyanophycece, 

 Scott and Zacharias have been able to detect structures resembling a nucleus. 



According to Eiitschli, the central portion of the protoplasmic contents of the 

 bacterium cell is to be regarded as of the nature of a nucleus, in that it takes up 

 very readily certain aniline dyes. It should be noted, however, that such stains 

 as hfematoxylin, carmine, saflranin have but little staining power for the contents 

 of the bacterium cell, compared with such stains as gentian violet, fuchsin, &c., 

 which stain them deeply, but which also stain the protoplasm of the cells of higher 

 plants almost as deeply as the contents of the bacterium cell. This seems to show 

 that the bacteria contain very little of the chromatic substance which is found in 

 the nuclei of the higher plants. The author of this paper has for some time 

 been working at the bacteria in the hope of elucidating this point, and has 

 obtained a bacillus in which a distinct nuclear structure can be observed. 



The bacillus referred to forms a thin scum on the surface of water containing 

 Spirogyra in a state of decay. The cells, which consist of short rods, occur either 

 singly or in pairs. They are about 2-5 to 3 |t in length, and from 1-3 to 1'5 ^i in 

 diameter, and when seen in a fresh state one or more brightly refractive granules 

 can be observed in each cell. In cover-glass preparations stained witli fuchsin, all 

 stages in the division of the bacillus could be observed. The preparations should 

 be made during the earlier stages of the development of the scum on the surface of 

 the water, while the bacillus is in a healthy state of division. 



In the centre of each cell a substance deeply stained by the fuchsin is Jibund. 

 This in young cells consists of two rods placed side by side, with a less deeply 

 stained substance between them, the whole being surrounded by a very thin 

 membrane which is only visible at the two ends. This is the structure which we 

 may call a nucleus. It is surrounded by a space containing a substance which is 

 only slightly stainable, and this again is surrounded by a deeply-stained membrane, 

 outside which is the slightly stained gelatinous envelope. Previous to its division 

 the cell elongates ; the nucleus also elongates and contracts slightly about the 

 middle of its length. A dumb-bell shaped structure is thus obtained. The two 

 rods divide completely, so as to form two groups, containing two rods each, which 

 remain connected together for some time by the less deeph'-stained portion of the 

 nucleus. The constriction becomes more and more pronounced, until finally the 

 "ywo halves of the nucleus are completely separated. The outer capsule or cell- 

 wall has meanwhile been contracting towards the middle, the contraction keeping 

 pace with the division of the central mass. This contraction goes on until at a 

 certain stage a delicate transverse partition appears, dividing it into two ; each 

 half contains one of the halves of the original nucleus. Ultimately the two halves 

 become completely separated, and two new cells are formed. 



In the majority of cases the cells are completely separated before the division 



