ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 531 



indicated by clear spaces, while nearer still are found granular and dumb- 

 bell shaped bodies intermediate between the true chloroplast and the 

 chondriosome ; finally in the dermatogen we have the thread-like or 

 spindle-shaped chondriosomes. The leucoplasts of the root have a dark 

 outer membrane enclosing clear bur, not homogeneous contents, and are 

 connected with one another bv thin sharply defined threads ; their origin 

 is identical with that of the chloroplasts of the leaf and stem. These 

 results seem to indicate some close relationship between the cell-substance 

 and the structures embedded in it. 



Nuclear Division in the Polypodiacese.* — R. de Litardiere con- 

 tributes a short note upon the nuclear division of the meristematic 

 tissues of Pteris multifida, Asplenium bulbiferum, Adiantum cuneatum, 

 and Dryopteris filix-mas. The chromatic network appears to be com- 

 posed solely of chromatin, and is associated with one large or two or 

 three small nucleoli of varied shape and separated by large lacunas. The 

 spireme stage resembles that in Osmunda cmnamomea. During prophase 

 the nucleoli stain readily. Longitudinal division occurs after the dis- 

 ap[)earance of the nuclear membrane and a little before metaphase. The 

 number of chromosomes immediately after anaphase is 52 in Pteris, 

 64 in Asplenium and Adiantum, and 72 to 76 in Dryopteris. Distribu- 

 tion of chromatic substance is effected by anastomoses of out-growths of 

 the chromosomes. Subsequent phenomena resemble those described by 

 Mano for P/iaseolus and Solanum, but contrary to Wager's observations 

 in Phaseolus, nucleoli and interchromosomic vacuoles appear at an early 

 stage. 



Plasma-streaming in relation to Statoliths.! — A. L. Heilbronn 

 has investigated the cause of the movement of statolith starch-grains by 

 direct observation of living plants maintained in a normal position. 

 The first series of experiments was connected with portions of the starch- 

 sheaths and root-tips of Vicia Faha and Phaseolus multiflorus. When 

 twisted 180° from the normal position, the statolith grains begin to 

 move after an interval of ten to fifteen minutes ; they usually glide 

 round the cell-wall, but a few traverse the cell-cavity by means of the 

 plasma-strands, and at the end of thirty -two to forty minutes are nearly 

 all resting on the lower cell-wall. If the normal position is resumed 

 the grains immediately pass once more to the lower cell-wall, but instead 

 of remaining there, they stream upwards with the protoplasm ; this 

 streaming reaches its greatest rapidity in one-and-a-half hours, and then 

 slowly decreases until the grains once more assume their normal position, 

 after iiaving traversed the cell-walls five or six times. 



The second series of experiments dealt with entire, uninjured seed- 

 lings oi Calceolaria ehelidonioides and Verbascum Thapsus, and, as before, 

 the grains slowly streamed to the lower wall, when the plants were 

 moved from the normal position ; when the plants resumed their original 

 position, the grains likewise sti-eamed back again, but no subsequent 



* Comptes Reudus, cliv. (1912) pp. 1097-1100. 



t Ber. Deutsch. Bot. GeselL, xxx. (1912) pp. 142-6. 



