1896.] MICEOSCOPICAL JOURNAL. 39'J 



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

 Erlich's methylen blue method by the investigfators in the 

 Marine Biolog-ical Laboratory at Woods HoU, Mass;,, may 

 be of g-eneral interest. 



The method has been successfully applied during- the 

 past summer to the study of the nervous system in a g-reat 

 variety of forms, including- vertebrates, Crustacea, annelids, 

 echinoderms and tunicates. 



Ehrlich's intra vitam methylenblue, prepared by Grubler, 

 was used for staining- the nerve tissues. The stain was 

 applied by injecting- a l->4 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 streng-fh of the solution 

 were determined by experiment for eachanimal and tissue. 

 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 

 bring-ing- the stain in contact with it in a solution of a 

 streng-fh suitable for obtaining- the best results. 



The abundant supply of oxyg-en to the staining- tissue 

 was of g-reat importance in some cases, while in others it 

 seemed to make little difference. 



It was found, as sug-g-ested by Dr. C. Huber, that animals 

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

 lig-ht. 



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 caug-ht 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 dog-fish, active animals were killed by 

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



