606 Journal of Applied Microscopy. 



dividing nuclei appear dark green, the spindle a dark red, and the corpuscles at 

 the poles dark green or violet, sometimes surrounded by an orange rose tint. 

 Upon adding acid alcohol (100 cc. alcohol and 1 cc. HCl.), the excess of 

 methyl green is removed in a very few seconds, the spindle takes on a brighter, 

 purer color, and the corpuscles at the poles become more distinct. This com- 

 bination gave better results than the popular safranin-gentian violet-orange, or 

 the Heidenhain's iron alum haematoxylin. 



Observations were made upon the two nuclear divisions, by which the four 

 pollen grains are formed from the pollen-mother-cell in Nymp/iea, JVuphar, 

 and Limnodorum. In Nymphea multipolar spindles are quite frequent, but they 

 are not always followed by the bipolar stage. 



The illustrations, which seem rather small and indefinite for such a disputed 

 subject, show numerous centrosomes, some with and some without radiations. 

 The occurrence of multipolar spindles is not considered a sufficient argument 

 against the presence of centrosomes. The writer concludes that there are in the 

 higher plants, differentiated centers, which function like the centrosomes of lower 

 plants and of animals. c. j. c. 



Hartog, M. Nuclear Reduction and the Func- After referring to the three modes of 

 tion of Chromatin. Nat. Sci., 13: 1 15-120, chromatin reduction, the writer sug- 

 ^ ■ gests that the linin is the important 



substance, the fair and equal division of which is the final cause of karyokinesis. 

 The splitting of a viscid thread presents great mechanical difficulty. If we 

 suppose a polarity in the chromatin granules, which, after splitting, tend to recede 

 from each other, the thread would be split and distributed. If we regard the 

 linin as the transmitter of hereditary qualities, and ascribe to the chromatin 

 granules a mechanical function, we avoid the difficulty encountered in attribu- 

 ting hereditary qualities to the chromatin, which is so subject to periodic growth 

 and atrophy. c. j. c. 



A Guide to the Study of Lichens. Albert Now that this book has appeared, there 



Schneider, M. D., Phil. D., Professor of are very few, if any, things left which 



Botany, Materia Medica, and Pharmacos;- ^, , , • n 1 i. a- 4. ^^• \^ 



nosy. Northwestern University School of the rambler IS likely tO meet tO which 



Pharmacy. Pp. XII, 234, with 11 plates, he cannot find a "guide," and if there 



Bradlee Whidden, Boston, 1808. , r • • m 1 *« 



' ^ be any group ot organisms visible to 



the naked eye to which it would appear almost impossible to prepare a guide, it 

 seems as though the lichens must be that group. When one considers that their 

 distinctive characters are principally microscopic, the algae and the spores, the 

 difficulty of preparing a satisfactory guide, with analytical keys, which can be 

 used by amateurs, becomes apparent. Nevertheless the author has made it 

 perfectly possible for these persons to become familiar with the more common 

 genera of the group through a study of their macroscopic features alone. 

 Although many species are described, the keys extend only to the genera. If 

 the student have a compound microscope he can, of course, make his identifica- 

 tions with much greater certainty, but in this case he will probably prefer to use 

 the author's " Text-book of Lichenology," of which this guide appears to be a 

 simplified condensation. About fifteen pages are devoted to a discussion of the 



