8 If. M. WOODCOCK. 



also tried, but only with indifferent success. Material was 

 left in sublimate and acetic twenty to forty minutes, and in 

 Flemming two to four hours. That fixed by the former 

 method was usually stained in bulk with borax- or para- 

 carmine, but material by the latter generally first on the slide. 

 If evagiuated Gregarines were still in the trophic condition 

 (see below, pp. 13 and 20) the nuclei were easily visible; if, 

 on the other hand, the parasites had commenced to sporulate, 

 it was usually necessary to cut the cysts before they could be 

 examined. In sections of advanced cysts stained whole the 

 nuclei were usually nicely differentiated ; in earlier stages, 

 however, the nuclei, for some reason or other, Avere indistinct 

 and the sections had to be restained. 



Sections were generally cut 3-4 /n thick, but occasionally 

 more. In experimental cutting of the blood-vessels and. 

 of the gut, undertaken in the hope of finding very young 

 and minute forms, the usual thickness was 10-12 fx. As 

 a rule the cutting presented no difficulty ; only when the 

 parasites were in the retractor muscles did I find it advisable 

 to paint the block with a solution of collodion and gum- 

 mastic. 



For staining on the slide the combination most frequently 

 used, and the one which gave the best results, was Heiden- 

 hain's iron-lnematoxylin method, followed by orange or eosin. 

 Thionin and orange rendered good service, as did also Kleiuen- 

 berg's hsematoxyliu, the slides being immersed in the latter 

 for a long time, forty-eight hours or so. Safranin, although 

 made up in two or three different ways, was rather diffuse, 

 and never etained the nuclear reticulum, but only the karyo- 

 some. Neither Auerbach's mixture (methyl-green and acid 

 fuchsin) nor Komanowsky's stain was of much service as a 

 " double " stain. I find that methyl-green cannot be relied 

 on as a chromatin staiu unless used fresh on the living animal, 

 and this was quite unsuitable for Cystobia. Komanowsky's 

 stain also, though well adapted for blood-films and smear 

 pre])arations, is most unsuitable for tissue parasites or where 

 sections are required. Neither for Gregarines nor for Myxo- 



