448 MRS. H. L. M. PIXELL-GOODRICH ON 



very intensely by these methods, which are therefore not always 

 convenient. In these cases Ehrlich's, Mann's, or Delaiield's 

 luematoxylins have given better results. Carmine stains have 

 always proved disappointing. As a rvile counter-staining was 

 not found to be an advantage, the cytoplasm being sufficiently 

 stained by the hjematoxylin. 



Plasmotomy. 



All Chiton examined from October 1914 to April 1915 were 

 heavily, if at all, infected. In only two cases was endogenous 

 multiplication still proceeding, and these specimens were obtained 

 and fixed during October. One of these (Chiton Y) contained 

 also many stages in sporogony and even some ripe spores ; the 

 other (Chiton X) was crowded chiefly with plasmodia, Avhich gave 

 a white appearance to the liver. Most of the plasmodia were 

 irregular in outline, but they varied much in shape and size 

 (PI. I. figs. 1 & 2). Scattered through them were nuclei con- 

 sisting of masses of chromatin, round each of which could be 

 distinguished a clear space. At this stage the nxicleus has no 

 sign of a membrane. Frequently these nuclei were dividing by 

 a simple method of mitosis. In vain have I searched through 

 hundreds of sections to find any trace at this stage of the beautiful 

 spindles wliicli have been figured for some Haplosporidia (2) (18). 

 Swarczewsky states that Chatton (5) must have missed them in 

 Caullerya mesnili ; but such does not necessarily seem to be the 

 case, for I do not think that they can have been passed over in 

 MincJdnia. 



When about to divide, the mass of chromatin separates into 

 two parts, which graduallj^ move away from one another, but for 

 some time are connected by a slender tliread (centrodesmose). 

 It has not been possible to demonstrate the centrosomes con- 

 tained in these chromatin masses by means of differential 

 staining, although one would expect them to be present. 



When a plasmodium has attained a certain size, or from other 

 causes, it breaks up into daughter plasmodia, each with seveial 

 nuclei (fig. 2). All these trophic stages ai'e quite naked and 

 their outlines generally ii-regular. It seems clear that they flow 

 along to some extent, probabl}' only very slowly, by putting foith 

 pseudopodia. Sometimes between closely apposed lobes of the 

 liver a plasmodium becomes very elongated and narrow (fig. 1). 

 No doubt want of space often determines the breaking up into 

 daughter plasmodia. It is rare to find one longer than 100 fx or 

 wider than 50 /,(. 



During this endogenous multiplication of the parasite the 

 host's phagocytes become very active and multiply lapidly, some- 

 times forming clumps. They appear to make a vain attempt to 

 enoulf the parasites, and occasionally one is observed flattened 

 against a plasmodium. 



Tliere is a certain amount of evidence to show that solid 



