ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 505 



Eyre, J. — Pond Dredging and Collecting. 



[For more delicate work or for use in ponds, &c, comparatively free from weeds, 

 a large-sized test-tube might be substituted for the bottle, and should be 

 fastened to a short thin length of bamboo as follows : — " Take a 6 in. length 

 of caoutchouc tubing, and make a cross cut three-quarters through, at about 

 an inch from one end; then another at right angles to the first along the 

 other 5 inches; the result is a short piece of tube with a 5 in. slip of gutta- 

 percha. The tube is slipped over the end of the rod, and the free end of 

 the flap is pushed between the rod and the tubing, the test-tube placed in 

 the loop so formed, and the strip drawn tight and fastened off."] 



Sci.-Gossip, 1888, p. 69. 

 Eousselet, C. — Pond Dredging and Collecting. 



["Hints on collecting Infusoria, Rotifera, and Polyzoa, the result of my expe- 

 rience in this interesting pursuit."] 



Sci.-Gossip, 1888, pp. 54-5. 



(2) Preparing Objects. 



Demonstrating Nuclein and Plastin.* — Dr. E. Zacharias in discuss- 

 ing the properties and mode of origin of nuclein and jdastin, remarks that 

 both substances are undissolved when the cells are treated with artificial 

 gastric jnice. Under the action of gastric juice, or of O^-O'S per cent, 

 hydrochloric acid, parts containing nuclein present a sharply defined 

 appearance, while bodies which contain plastin but no nuclein swell up 

 and grow pale. Nuclein swells up in 10 per cent, salt solution, in 

 solution of soda and in dilute caustic potash. Plastin, on the contrary, 

 does not swell up in 10 per cent, salt solution, and is only soluble with 

 difficulty in alkalies. Both are soluble in concentrated hydrochloric acid, 

 but in a mixture of 4 vols. HC1 to 3 vols. H 2 the nuclein only dis- 

 appears. When fresb, bodies containing nuclein swell up in distilled 

 water. Long preservation in spirit is detrimental to these reactions. 

 Nuclein takes up pigments with avidity, but this property is in no way 

 confined to parts containing nuclein. All the cell protoplasm becomes 

 stained by the prolonged action of pigment. It cannot therefore be con- 

 cluded that nuclein is present because the nucleus becomes stained, but 

 if it do not, it may be inferred that it is absent or present in small quantity. 



Substances with the foregoing properties have hitherto only been 

 demonstrated in the cell-nuclei ; plastin, on the other hand, is a con- 

 stituent of the whole cell-plasma. The existence of nuclein in bottom 

 yeast, in Phycochroruacea), milk, and yolk-corpuscles of animal ova 

 appears to clash with the former statement. In the two last cases the 

 substance in question differs in its reactions from nuclein. The author 

 found it both in germinating and in bottom yeast. By extracting 

 germinating yeast with ether alcohol, then soaking in water, and staining 

 with Grenadier's hematoxylin, the cell-nuclei are rendered evident. 

 The action of the digestion-fluid failed to demonstrate the nucleus ; but 

 in bottom yeast the nucleus was found to coutain nuclein. Bottom 

 yeast extracted with alcohol ether, digested, and then placed in a • 3 per 

 cent, salt solution for 24 hours, showed in the bright swollen-up plasma 

 residue corpuscles of irregular shape, and with the characteristic bright- 

 ness of nuclein. By adding pure strong hydrochloric acid the corpuscles 

 lose the brightness, the plasma becomes clearer, and then disappears 

 along with the corpuscles. A 10 per cent, salt solution acting on 

 digested material which has been extracted with alcohol-ether causes the 

 corpuscles to swell up while the rest of the plasma remains well defined 



* Bot. Ztg., xlv. (18S7) pp. 282-8, 297-304, 313-9, 329-37, 345-56, 361-72, 

 377-88 (1 pi.). 



