ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 445 



nuclear bridges connecting contractile portions of the nucleus with con- 

 tractile portions of the cytoplasm. There is a connection by means of 

 the cytoniitom between structural elements of the nucleus and the "cen- 

 trosomes." The latter are spherical differentiations of the cytoplasm. 

 There are no isolated nuclei in the polymorphic leucocytes. No nuclear 

 membrane was to be seen. 



Theory of Cell-division.* — Angel Gallardo regards cell-division as 

 "essentially a bipolar phenomenon of an electro-colloidal character." 

 He assumes a negative electro-colloidal charge for the chromatin and an 

 opposite one for the cytoplasm and centrosomes. He refers to similar 

 suggestions by Ziegler, Hartog, Delage, and others. 



Skin of Pleurodeles.f — J. Gogorza has made a study of the minute 

 structure of the skin in this newt, with particular reference to the glands, 

 the nerve-endings, and the chromatophores. 



Mucous Epithelium. J — Aug. Lelievre and Ed. Retterer find that 

 the mucous cells in the genital duct of the female guinea-pig start from 

 the state of epithelial cells with vesicular nucleus and granular baso- 

 philous cytoplasm. The granular cytoplasm elaborates hyaloplasm which 

 is transformed into mucus, while the nucleus is reduced to a block of 

 chromatin. Finally the mucin liquefies ; the reticum and the nucleus 

 are disintegrated. The mucus which lubricates the tract is thus the 

 result of " holocrine " secretion. 



Tactile-cells of G-randrys' Corpuscles. § — N. Nowin describes the 

 minute structure of these cells in the bill of the duck, with particular 

 reference to the network of fibrils within them. The fibrils stain like 

 those in epithelial cells in the skin ; there are intercellular bridges con- 

 necting the tactile cells to one another, and the tactile disks are only 

 apposed to, not organically united with, the tactile cells. All this indi- 

 cates that the tactile cells are epithelial in origin and nature. 



Sensory Organs of Onychodactylus.|| — K. Okajima gives an elabo- 

 rate account of the minute structure of the olfactory organ, ear and eye 

 of this Japanese amphibian, both in its adult and larval state. 



Granules in Nerve-cells.f — W. M. Smallwood and C. G. Rogers 

 have studied the metabolic bodies in the cytoplasm of nerve-cells in 

 Chromodoris zebra and other Bermudas Gastropods, Octopus rugosus, 

 and a leech Semiscolex. They find that the presence of granules, either 

 pigmented or unpigmented, is general. An equally constant feature of 

 the cytoplasm is the vacuole. In some cases vacuolation may be a mark 

 of pathological conditions, but it is more generally a sign of previous 

 activity on the part of the cell. The contents of the vacuoles represent 

 granular matter in process of transformation to be used as food-matter 

 by the cell protoplasm. The granules may be caused to break down and 



* Archiv Entwickl., xxviii. (1909) pp. 125-56 (9 figs.). 



t Mem. R. Soc. Espan. Hist. Nat., vi. (1909) pp. 67-103 (3 pis. and 8 figs.). 



% C.R. Soc. Biol. Paris, lxviii. (1910) pp. 59G-9. 



§ Anat. Anzeig., xxxvi. (1910) pp. 217-25 (5 figs.). 



|| Zeitschr. wiss Zool., xciv. (1909) pp. 171-239 (2 pis. andG figs.). 



«| Anat. Anzeig., xxxvi. (1910) pp. 226-32 (3 figs.). 



