ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 771 



and N. virgula — are found. From the group of the Microsporidia it appears 

 to be necessary to remove Amoehidium and Botellus ; Lecaniascus polymorphus, 

 which is an Ascomycete ; the parasite found by M. Balbiani in Tortrix viri- 

 diana ; and, lastly, the organisms found by Leydig in the bee, -which have 

 been wrongly comj)ared to Closterium lunula. 



BOTANY. 



A. GENERAL, mcluding the Anatomy and Physiology 



of the Phanerogamia. 



a. Anatomy.* 



CI) Cell-structure and Protoplasm. 



Structure of the Nucleus-t — According to Herr E. Zacharias, the cell- 

 nucleus of both plants and animals is composed of two distinct substances, 

 plastin and nuclein. After treatment with artificial gastric juice, there 

 remain in the cells, in addition to other substances, two others undissolved, 

 readily distinguished from one another by their micro-chemical j)roperties. 



One of these, nuclein, occurs exclusively in those elements of the nucleus 

 which form, during division, the colourable filament-loops. In consequence 

 of the nuclein which they contain, these portions retain, on treatment with 

 gastric juice or hydrochloric acid, a sharply defined, peculiarly shining appear- 

 ance. During the action of the gastric juice, numerous drops of an oily appear- 

 ance are excreted from the cell-protoplasm, which render the form less clear. 

 If these drops are removed by washing with alcohol or ether, and examined 

 in dilute hydrochloric acid, it is seen that the bodies of the j^eculiar shining 

 appearance described exist only in the nucleus. The other substance, 

 plastin, is an essential constituent of the entire protoplasmic cell-contents, 

 including the nucleus and chromatophores. Gastric juice or dilute acids 

 do not cause in it the characteristic appearance of nuclein. Bodies which 

 contain plastin but no nuclein appear ijale and swollen after treatment with 

 these reagents, so that the diifereuce between the two is usually seen after 

 remaining in them for a time. Plastin also differs from nuclein in its 

 behaviour towards other swelling or dissolving reagents ; it does not swell 

 in preparations treated with gastric juice on addition of a 10 j^er cent, 

 solution of sodium chloride, and does not disappear, like nuclein, on treat- 

 ment with a mixture of 4 parts (in vol.) of the concentrated hydrochloric 

 acid of commerce and 3 parts of water. Plastin is, however, dissolved, 

 after some time, by pure concentrated hydrochloric acid. It dissolves less 

 easily in alkalies than nuclein, and by this means the latter can be removed, 

 while the former remains behind unchanged. 



Nuclein possesses the property of absorbing eagerly certain pigments, 

 especially methyl-green, which was demonstrated by the author in sections 

 of the root of Phajiis and of Tradescantia. Zacharias's nuclein corresponds 

 to the "soluble nuclein" of Miescher, his plastin to the plastin of Eeinke 

 and the " difficultly soluble nuclein " of Miescher. 



The author confirms the observations of Schmitz, Strasburger, and 

 Zalewski, of the existence of a cell-nucleus in the Saccharomycetes ; but 



* This subdivision contains (1) Cell-sh'ucture and Protoplasm; (2) Other Cell- 

 conteuts; (3) Secretions; (4) Structure of Tissues ; and (5) Structure of Organs. 



t Bot. Ztg., xlv. (1887) pp. 282-8, 297-304, 313-9, 329-37, 345-56, 361-72, 377-88 

 (1 pi.). 



