170 Scientific Proceedings, Royal Dublin Society. 



protoplasmic remains and two impoverished nuclei suggestive of parasitic 

 stimulation. PI. XIII., fig. 7, is taken from a preparation of restored 

 type material of T. Scabies, and shows a cell occupied apparently by the 

 Plasmodium, judging from comparison with the appearance of the cells in 

 PI. XIII., fig. 6. 



The Spore-Balls. 



Martius describes the spore-balls as opaque grains witli a shagreen-like 

 surface, and formed of several larger and smaller globules. Together they 

 form the black or dark brown powder, each grain being about twice the 

 size of a starch-grain and " -^g - ^^g mm." in diameter. Berkeley describes 

 the spore-balls as hollow spheres with one or two apertures communicating 

 witli the interior — an error in description repeated by several subsequent 

 writers. Brunchorst, who made microtome preparations of the balls, saw 

 and described their true structure. Each spore-ball, ovate-oblong to more 

 or less spherical in shape, consists of hundreds of angular spores 3'5 /a 

 in diameter, firmly bound together to form a sponge-like body. The spore- 

 ball is not hollow but honeycombed by cavities or passages in communication 

 with one another and with the exterior. The spores are thus arranged like 

 trabeculee or strands traversing and enclosing the cavities. Unfortunately 

 Massee repeats the earlier erroneous description, even in the description of 

 the origin of the spore-ball from the plasmodium. The figures here given, 

 PI. XIII., fig. 2 (from Berkeley's own material), and PL XIII,, fig. 1, 

 show that the spore-ball is not a hollow sphere, but a sponge-like body, 

 the cavities or plasmogenetic intercellular spaces, as I have called them, 

 being the vacuoles of the sporogenous plasmodium. Massee speaks of 

 the appearance of the ripening spore-ball, as seen " in optical section," 

 and his mistake in description may be due to want of use of microtome 

 preparations. 



The inaccurate description of the spore-ball's structure made me doubt 

 the reliability of the observation by Massee of the earliest stage of the 

 invasion of the host-cells by the parasite. Massee says : " The earliest 

 condition observed in a cell of the host consists of a veiy few irregularly 

 globose protoplasmic bodies aggregated round the nucleus of the cell. 

 [His fig. 4, here reproduced in PI. XIII., fig. 4]. . . . When fixed and stained 

 these amoeboid bodies are seen to possess a single nucleus. . . . How these 

 amoeboid bodies gain an entrance into the cell of the host has not yet been 

 observed ; but sucli invaded cells are always the most internal of the cells 

 affected by the parasite, and are always immediately adjoining other cells 



