ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 661 



diseases are produced by parasitic elements which occur under 

 different forms in the blood. 



Vaccinal Micrococci. — M. Straus presented to a recent meeting 

 of the Societe de Biologic at Paris a series of microscopical prepara- 

 tions of the vaccinal pustule from the calf, at different stages of its 

 progress, in which the presence of the special micrococcus could 

 readily be observed. The method of preparation adopted was to 

 place the excised fragments of skin in absolute alcohol, to cut sections 

 and stain them by Weigert's method (methylamine violet), and then 

 discolouring them until only the nuclei, the bacteria, and micrococci 

 remain visible. Under a high power, the latter were visible as 

 extremely minute points, tinted blue, about a thousandth part of a 

 millimetre in diameter, and grouped in colonies. They were seen in 

 the borders of the inoculation wound, and in the Malpighian layer, 

 and subsequently could be traced passing into the subjacent cutis, 

 especially in the lymphatic spaces. The multiplication and extension 

 of the organism seemed to coincide closely with the development of 

 the pustule. 



Mucorini.* — Professor G. Bainier has published a useful mono- 

 graph on these fungi. In a general introduction he briefly considers 

 the systematic position of the Mucorini, their reproductive organs, 

 mode of life, and methods and results of cultivation. The bulk of 

 the work is occupied with the description of the species, twenty-seven 

 of which are figured. It concludes with remarks on the importance 

 of the Mucorini in the economy of nature. 



Algae. 



Disengagement of Oxygen by Vegetable Cells in the Micro- 

 spectrum.t — T. W. Engelmann describes experiments on this subject. 

 He has studied the relation between the wave-length and the assimi- 

 lative action of the luminous rays by the " bacteria method." J For 

 this purpose he has made use of a microspectral apparatus, con- 

 structed under his directions by Zeiss of Jena. The apparatus forms 

 a microspectrum at the plane of the object on the stage, and replaces 

 in use the ordinary illuminating apparatus (mirror and diaphragm) of 

 the Microscope. It is composed of, 1st, a plane mirror ; 2nd, an 

 arrangement with two slits, viz. a, a slit, with both sides movable by 

 means of a micrometric screw and the breadth of which can be 

 adjusted (with a range of 2 mm.) to about -001 mm. b. A 

 slit movable, perpendicular to a ; 3rd, a collimator lens ; 4th, 

 a direct-vision prism ; 5th, an objective forming the spectral image 

 of the slit. As it is useful to be able to vary the absolute size of the 



* Bainier, G., ' Etudes sur les Mucorinees.' 4to, Paris, 1882, 136 pp. and 

 11 pis. See very full abstract by Dr. Zimmerman in Bot. Centralbl., xi. (1882) 

 pp. 115-32. 



t Rev. Internat. Sei. Biol., ix. (1S82) pp. 465-7. Pfliiger's Arch. f. Physiol., 

 xxvii. (.1882) p. 485. Bot. Ztg., xv. (1882; pp. 419-26 (1 rig.). 



J See this Journal, i. (1881) p. 962. 



