744 MURIEL ROBERTSON. 



serous blood that lias been allowed to stand exposed in 

 the air. The addition of salt-solution to the blood some- 

 times causes the hgemogregarines to quit the corpuscle, but 

 never in lai'ge numbers. Altogether, it may be said that 

 H. nicorise shows far less tendency to become motile 

 in the blood than the majority of the species of haemo- 

 gregarines. 



The greater parfc of the blood-films made were preserved 

 by the drying method and stained with Giemsa; a few were, 

 however, fixed while still wet in sublimate-acetic, and treated 

 by wet methods throughout. These wet films were stained 

 with iron hajmatosylin, and it has been clearly shown that 

 wet fixation followed by heematoxylin, haeoialum, or other 

 suitable stain, gives far truer ])ictures than those obtained by 

 the Giemsa method. All the detail of structure, etc., described 

 were worked out on the wet films. 



l*arts of the various oi-gans, such as the spleen, liver, and 

 lungs, were also preserved (in Flemming, corrosive-acetic, 

 and Bles's fluid) and sections made. Bles^s fluid was found 

 to give an exceedingly good fixation of the blood-corpuscles 

 and of the parasites they contained, especially in the tissue 

 from the lung. When stained with hajmalum a very clear 

 and precise picture Avas obtained, and the results derived 

 from a study of the films could thus be corroborated and 

 criticised by means of the section material. 



In the stained fihns it can be seen that the parasite is sur- 

 rounded by a delicate sheath or capsule. The nature of this 

 capsule shows the greatest possible variation in different 

 members of the genus H asm ogre gar in a. In some species 

 it is a thick retractile envelope, which opens to let out the 

 enclosed parasite when the motile phase is adopted. Even 

 when the capsule is more delicate it is often capable of 

 persisting for a time after the hgemogregarine has escaped. 

 This has been observed by many workers; Castellani and 

 Willey (4) have shown it in H. mirabilis, Dobell, in a form 

 from Boa constrictor (6) ; I have myself seen the same 

 thing in H. triedrus. In H. nicori^ the capsule is rather 



