83 
varieties, one of the latter, D. exaltatum Barbeyi, being also pro- 
posed as new,* and all the others based on species proposed by 
various authors, every one of those characterized by Torrey and 
Gray, Asa Gray and Sereno Watson being thus reduced. Those 
retained are D. bicolor Nutt., D. cardinale Hook., D. decorum F. 
and M., D. recurvatum Greene, D. azureum Michx., D. Penardi 
Huth, D. exaltatum Ait and D. tricorne Michx., D. hesperium A. 
Gray, he does not feel sufficiently acquainted with to reduce. 
Nov B; 
Recherches Experimentales sur la Physiologie, La Morphologie et la 
Pathologie des Diatomees.—X. Du noyau chez les Diatomees. 
Miquel, P. (Annales de Micrographie, 5: 437-462, 3 plates. 
Oct., 1893). - 
This is an exceedingly interesting contribution to the subject 
of Diatomology. Mr. Miquel has discussed very fully the subject 
of the nucleus of the Diatoms, and we feel that much has been 
added of importance to this branch of the subject. He speaks 
of the few researches that have been made upon the proto- 
Plasmic contents of the diatoms, as most microscopists have 
busied themselves with the resolving of the finer sculptured forms. 
The author's researches have been made upon pure cultures of 
the plants, and he has devised some methods of technique in the 
Study of the nucleus, which may be of interest. The use of methy- 
lene blue is recommended as a protoplasmic stain, both general 
and to differentiate the various parts. The author maintains that 
the solution should be very weak; indeed just enough of the 
coloring matter to tinge the fluid in which the plants are growing. 
is Strength is not enough to kill, and the staining takes place 
Sradually, and there is no distortion. By this reagent the various _ 
Portions of the protoplasm are differentiated. Methylene blue in 
water; ia water and weak boric acid, and in water with weak 
ammonia are the three solutions used. In carefully stained speci- 
mens the protoplasm is just tinged; some of the chromatic ele- 
ments acquire a darker blue and sometimes even a violet hue, the 
nucleus being still darker, sometimes being almost black. 
Re ne hen eee 
“ on has subsequently raised this to specific rank as D. Barbeyi _ eet a 
