METHOD OF CELL DIVISION IN MONIEZIA. 131 



phuric, Zenker's fluid, Zenker plus an excess of acetic acid, and 

 a modification of Zenker's fluid by Dr. King. 1 



None of my sections have been cut over 4 micra thick; many 

 of them are thinner. Pieces of the worms about 3-6 mm. in 

 length were embedded serially beginning at the scolex or the 

 neck region and extending back some 35-40 cm. usually, in- 

 cluding the beginning of the proglottids with fully formed 

 embryos. Pieces were then selected at intervals and cut; 

 later, if examination warranted, the intervening pieces were cut. 

 In this way practically one entire worm has been cut and studied, 

 while from a considerable number of other worms incomplete 

 series have been made as described. I have used both longi- 

 tudinal and cross sections. 



A number of staining methods have been tried on Moniezia, 

 some of which gave good results, while others succeeded only 

 indifferently. I have been unable to get good preparations 

 with Kernschwarz, although this stain served me well on Tcenia. 

 The other stains used include Delafield's hsematoxylin, haem- 

 alum, thionin, Bismarck brown, iron haematoxylin alone and 

 counterstained with Lichtgriin or Bordeaux R, a modification 

 of Conklin's picro-haematoxylin method for staining eggs in 

 toto? Ehrlich-Biondi, and the Flemming triple stain, safranin 

 gentian-violet and orange G. 



Of these stains, iron haematoxylin is the best general stain and 

 most reliable, but for certain phases of the work it is not suffi- 

 ciently differential. I have found picro-hsematoxylin and the 

 safranin gentian-violet mixture especially useful in connection 

 with it. (In most cases I find that the orange G of the triple 

 stain detracts from rather than adds to its value.) 



1 Dr. King uses two solutions, as follows: (i) Four per cent, potassium bichromate; 

 (2) corrosive sublimate, 4 gr., glacial acetic acid, 20 c.c., water, 76 c.c. The two 

 solutions are mixed equally and allowed to act for one to two hours as the mixture 

 penetrates rapidly. For convenience, I shall hereafter call this mixture "King's 

 fluid." 



2 This is an application of the in toto method to sections containing eggs. It 

 consists of mordanting the sections for a short time too long is injurious in 

 aqueous picric acid solution. After staining the sections may be decolorized in 

 this same solution and then blued in tap water. It gives the desired differentiation 

 between yolk and chromatin, although not with the characteristic colors of Conk- 

 lin's stain. 



