1890.) Microscopy. 1217 
notwithstanding these occasional slips, Professor Perkins has done a 
very useful work in a line where his example may well be followed. 
North American Pselaphidae.— Messrs. E. Brendel and H. F. 
Wickham have lately published in the Bulletin from the Natural History 
Laboratories of the Iowa State University (Vol. L, pp. 216-304, and 
Vol. II., pp. 1-84) a Monograph of the Pselaphidz of North America, 
which shows evidence of much careful work. Seven plates from 
stipple drawings by Dr. Brendel, the senior author, fairly well represent 
the species described. This monograph will be a great help in the 
determination of species in this difficult family of beetles. 
MICROSCOPY.! 
Direct Division of the Nucleus in the Enteric Epithelium 
of Rhabdonema nigrovenosum.?—Prof. Hoyer finds in the epi- 
thelium lining the alimentary tract of Rhabdonema good material for 
demonstrating the so-called ‘‘direct’’ division of nuclei. Hoyer 
mits, however, that his preparations are not conclusive evidence 
of such division. 
Following Kultzitzky's method, Prof. Hoyer killed the Nematodes 
in ** strong alcohol," stained in alcoholic borax-carmine 24hs., decol- 
orized in acidified alcohol rh. (strong alcohol + 1% HCl.), transferred 
to glacial acetic acid (15m.), then to a mixture in equal parts of glacial 
acetic acid with creosote, then to pure creosote, and finally mounted 
in creosote balsam. 
Such treatment, we should think, would be likely to bring out 
** direct'' division. We agree with Hoyer that the case needs 
further investigation. 
Culture of the Larva of Ascidians, Worms, Echino- 
derms, etc.®—Dr. Ch. Julin has found the following method, sug- 
gested by Prof. Giard, to be very useful in rearing larvze of various 
kinds. Material for the study of the formation of the colonies of 
compound Ascidians may be easily obtained in this way : 
Collect the free larve in a pipette at the time of hatching, and place 
them in covered watch-glasses containing clean sea-water. Keep them 
protected from the light (half-dark). ‘‘ Thus kept, they develop quite 
1 Edited by C. O. Whitman, Clark University, Worcester, Mass. 
2 H. Hoyer. Anat. Anz., V., 1, Jan. 1890, p. 26 
3 Extracted from a letter from Dr. Ch. Julin to Dr. Minot, dated Sept. 3, 1889. 
