1890.] MICROSCOPICAL JOURNAL. 399 



Methylen Blue. — A few points observed in the use of 

 Erlich's methylen blue method by the investigfators in the 

 Marine Biological Laboratory at Woods Holl, Mass., may 

 be of general interest. 



The method has been successfully applied during the 

 past summer to the studv of the nervous system in a great 

 variety of forms, including vertebrates, Crustacea, annelids, 

 echinoderms and tunicates. 



Ehrlich's intra vitam methylen blue, prepared by Grublcr, 

 was used for staining the nerve tissues. The stain was 

 applied by injecting a l->2 per cent solution of the methy- 

 len blue made in normal salt solution, into the blood ves- 

 sels, body cavity or lymph spaces or by immersing small 

 animals or excised pieces of nerve tissue in a weak solu- 

 tion. 



The method of application and strength of the solution 

 were determined by experiment for eachanimalandtissue. 

 During the action of the stain, the animal or tissue was 

 kept as nearly as possible in its normal condition. Every- 

 thing seems to depend on keeping the tissue alive, and in 

 bringing the stain in contact with it in a solution of a 

 strength suitable for obtaining the best results. 



The abundant supply of oxygen to the staining tissue 

 was of great importance in some cases, while in others it 

 seemed to make little difference. 



It was found, as suggested by Dr. C. Huber, that animals 

 which live in the dark, stain better in the dark than in the 

 light. 



The relaxation of the tissues by the use of chloroform 

 or chloral hydrate seemed to be more favorable for the 

 staining of some elements of the nervous systen, while 

 others did not stain which stained in the unchloroformed 

 animal. 



It was found that recently caught and perfectly normal 

 animals stained more satisfactorily than those which had 

 been kept in confinement for some time, unless under very 

 favorable conditions. 



In the case of the dogfish, active animals were killed by 

 decapitation. The stain was applied by injecting a 1-^ 



