288 Journal of Applied Microscopy. 



the drop of osmic acid without coming in contact with the air. Thus is obtained 

 immediate and complete fixation of the blood elements. The drop of blood 

 mixed with the acid is then placed on a slide, covered, sealed, and examined- 

 The blood plates appear as pale yellow, minute bodies, that seem to possess more 

 motility than the ordinary red blood corpuscle. c. m. m. 



Histological Laboratory, Cornell University. 



University of Pennsylvania. — Methyl-acetic stain and fixative combined 

 has been used in cytological work on protozoa with some success. For tempo- 

 rary preparations, at least, the differentiation of nuclei is very rapid and clear. 

 The formula is : 



Sat. aq. sol. Methyl Green, lUO parts. 



Glacial acetic, - - 1 " 



Professor Conklin has found a combination of picric acid with Delafield's 

 haematoxylin to yield much better differential results than any other ha^matox- 

 ylin yet employed. For /// toto staining it is particularly superior, as the pene- 

 tration seems to be deeper and the danger of overstaining very slight — thus 

 obviating the necessity of destaining. The picric acid stains and renders trans- 

 parent the yolk in ova. This has already enabled workers who have tried it to 

 distinguish clearly many points which are totally obscured by the clouded effects 

 of haematoxylin alone. Nothing better has been found for chick embryos. 

 The following formula gives the best results : 



■ Delafield's haematoxylin, ) . 



. Distilled water, \ ^ 



Picric acid, 1 drp. for each cc. of the mixture. 



This may be used for a stock solution. Diluted to one-fourth and used for from 

 ten to twenty minutes, it gives splendid differentiation in chick embryos without 

 any necessity of decoloring. j. R. m. 



Professor J. C. Arthur of the Indiana State Experiment Station, Purdue 

 University, recently delivered a lecture before the Biological Association of 

 Depauw University on the biology of habit. H. H. z. 



In reply to your correspondent's query on page '202 of the November issue, 

 relating to the mounting of small Coleoptera and parts of insects, a paper was 

 published on this subject by Mr. Robert Gillo in the Journal of Alicroscopy 

 and Natural Science for July, 1885 (First Series, Vol. IV, page 151). I 

 think it probable that Messrs. Baillere, Tindall & Cox of King William street, 

 Strand, London, W. C. (the publishers) could supply your correspondent with a 

 copy. G. H. B. 



Bangor, North Wales. 



