LIFE-CYCLM OF " CYSTOBIA " 1HHEC4ULA RIS (mINOH.). 7 



parasites are usually in the respiratory trees or else attached 

 by a stalk to the coelomic epithelium. Those in the latter 

 position are always adults, and invariably more or less en- 

 veloped by a double layer of transparent epitlielium. Hence 

 they are much easier to remove and mount without damage 

 than are the unencysted adults of C. irregularis, for the 

 body-form is preserved unaltered, with the exception, occasion- 

 ally, of the free extremity. All that has to be done is to take 

 firm hold of the stalk of invagination with a fine pair of 

 forceps, and carefully break it away at its point of attach- 

 ment to the general epithelial layer. The parasite comes 

 away, of course, with the stalk and need not, itself, be 

 touched during the operation. It can thus be readily brought 

 either into a watch-glass or on to a slide, as required for 

 fixation. 



(6) Fixation and staining. — Adults were usually fixed 

 on the slide with osmic vapour by holding the slide inverted 

 over the mouth of a bottle containing a 1 per cent, solution 

 of osmic acid for five minutes. They were then washed well 

 with watei-, stained with dilute Ranvier's picro-carmine, dehy- 

 drated, cleared, and finally mounted in balsam. This pro- 

 cedure gave very satisfactory results. As an alternative 

 method, a saturated aqueous solution of corrosive sublimate 

 was used, to which had been added 5 per cent, of glacial 

 acetic acid. The objects were afterwards stained either with 

 carm-alum or with alcoholic para-carmine. Both these stains 

 differentiated the nuclei well. Some adults obtained from 

 Cucumarii\3, which had been previously preserved in 90 per 

 cent, spirit, were rather shrunken in outline. The nuclear 

 contents also were retracted away from the membrane, but 

 the cytoplasm was well preserved. I sectioned a few, and 

 stained on the slide. Thionin, followed by orange, was very 

 successful. 



For Gregarines in the blood-vessels, respiratory trees, or 

 elsewhere, aud for all cysts, either the corrosive sublimate 

 and acetic mixture referred to, or strong Flemming, was 

 generally bjst. Perenyi's iiuid and picro-sulphuric were 



