ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 713 



The great difference in the sizes of the sexes is also referred to, the 

 female weighing over six times as much as the male. 



Formation of and Reactions of Nuclei.* — C. Frommann finds 

 that the aiiplication of acids to nuclei of non-amcBhoid cells does not 

 result at first in a great change in the yellowish granules of the 

 protoplasm, but that, after the acids have acted for some time, they 

 become pale and can no longer be accurately distinguished from one 

 another, and the nucleus appears to be surrounded by a distinct 

 membrane. With amoeboid cells the action of acids results in the 

 appearance of a firm stroma and a firm more complete investing 

 membrane ; from the material of the protoplasmic granules new 

 nuclei as well as separate longer filamentar structures are formed, 

 or granules only are formed, and the protoplasm becomes clearer and 

 more homogeneous. It must be borne in mind that we have here to 

 do with artificial products. The author criticizes the views of Eobin, 

 and points out that structures, which we are bound to compare with 

 nuclei, are to be found in the living colourless blood-corpuscles ; this 

 has been proved by Strieker for non-defibrinated, and by Frommann 

 for defibriuated blood, and Flemming speaks very positively as to the 

 presence of nuclei in living leucocytes, whether in or out of the 

 vessels of the larvae of the salamander. 



If a homogeneous body, either spontaneously or after the action 

 of chemical or physical reagents, differentiates into a formed and a 

 homogeneous substance, the phenomenon may be explained by the 

 supposition that both bodies were present, but had the same re- 

 fractive index, or by supposing that the apparently homogeneous 

 body was really so, and that the appearance of formed elements is due 

 to a differentiation of its substance into elements which are more 

 highly refractive, and a clear substance which fills up the interspaces. 

 The author is inclined to accept the latter view as applying to what 

 obtains with nuclei, and supports it by various considerations. Ex- 

 periments with salt solutions show that, after the fusion of the whole 

 mass of the grains and granules with the nucleus, the whole structure 

 thus formed becomes converted into a nucleus with sharply defined 

 stroma and fii-m investment, so soon as spring or distilled water is 

 added to the preparation. Various other experiments are detailed, 

 the study of which is a matter of great importance for those who are 

 making observations or experiments in connection with the phenomena 

 exhibited by nuclei. 



Indirect Nuclear Division.! — E. Strasburger commences an essay 

 on the subject of the controversy with regard to indirect nuclear 

 division by an account of some specimens of the embryonic sac of 

 Fritillaria imjjerialis, which had been prepared by Herr Heuser. He 

 concludes from his numerous observations that it is very probable 

 that in all typical processes of the indirect division of the cell-nuclei 

 of plants there is a stage in which the segments of the nuclear 

 filament divide longitudinally. This process is not, however, always 



♦ SD. Jcnaihcli. Gesell. f. Med. u. Naturwiss., 1883 (1884) pp. 4-lG. 

 t Arch. f. Mikr. Anat., xxiii. (1884) pp. 246-304 (2 pla.). 

 Ber. 2.— Vol. IV. 3 b 



