546 



Since my earlier preparations were made for purposes of ana- 

 tomical rather than cytological study, the technique employed was not 

 wholly suitable for examination of the minuter details. A new supply 

 of material was therefore obtained from the Chicago Stockyards and 

 the living worms were fixed by various methods, viz., saturated aqueous 

 sublimate, sublimate with 5 °/o acetic acid, Gilson's fluid and Hermann's 

 fluid. This material was imbedded in paraffin and the sections variously 

 stained. The only stains, however, which proved at all satisfactory 

 were Delafield's haematoxylin and Heidenhain's iron-haematoxylin. 

 Among these methods of preparation, fixation in saturated aqueous 

 sublimate solution and staining with iron-haematoxylin, with slow ex- 

 traction in V4 — V2 °/o iron-alum aff"orded the best results. 



Examination of some fifteen series of slides from various regions 

 of the chain showed that amitosis was the characteristic method of 

 division of the nuclei, even in the developing reproductive organs. 

 Circumstances prevented me from continuing the work at that time, 

 but in 1902 I made a second examination of the preparations which 

 confirmed my earlier conclusions. In May of the present year the 

 preparations were subjected to a third examination with similar results. 

 In June a new supply of material was obtained with the hope of im- 

 proving the technique, the animals being removed from the intestine 

 of the sheep within ten minutes after its death and fixed at once 

 before they were subjected to any marked reduction in temperature. 

 Three fluids were employed for fixation, viz. saturated aqueous subli- 

 mate, Hermann's fluid and Graf's chrora-oxalic acid. Comparison 

 showed that the last named fluid was preferable to any of the others 

 employed and the following studies were confined to material fixed 

 by this method. My best preparations were obtained from material 

 which remained three hours in the fluid. 



With this material an extended study of nuclear division in the 

 proglottids was made. Series of pieces for sectioning were prepared 

 as follows: Uninjured chains were selected and from each of these a 

 piece long enough to include several proglottids was taken every ten 

 to fifteen millimeters from the scolex backward, the intervening pieces 

 being numbered and preserved for later use. The pieces were cut 

 into sections 3 f-i thick and it was found that they alforded a complete 

 history of the development of the proglottids. The difference in stage 

 of development between two adjoining pieces was very slight and the 

 series was without gaps. Leitz oil immersion lenses Y12 ^^^ Vie were 

 used for study ot the sections. All figures are camera drawings and 

 represent cases in which there was no room for doubt. Sections from 



