E. RAY LANKESTER, ON GREGARINID. 89 
This fact was denied by Stein,* who affirmed that the cysts 
burst only upon being subjected to the action of water. 
Jieberkiihn has, however, proved this statement to be 
erroneous, having kept cysts taken from Lumbricus in 
water for the space of five days, without any apparent change 
taking place in ,their form or size. I have frequently seen 
agglomerations of the Pseudo-navicule evidently in the same 
position as they were when contained in the cyst, which had 
itself entirely disappeared, probably by decomposition. On 
escaping from the cyst, the Pseudo-navicule contain no gra- 
nules (fig. 32); but the gelatinous fluid which they enclose 
appears to concentrate itself, and give rise to certain minute 
bodies, which, collecting towards the centre, form a nucleus- 
like mass. A change then comes upon the form of the Pseudo- 
navicula (figs. 29—31); it loses its symmetry, and becomes 
flaccid ; the external membrane becomes atrophied (fig. 31), 
“commence a s’atrophier,’ and assumes an irregular shape. 
I have not been able to trace the changes which these curious 
bodies undergo any further. . M. Lieberkiihn, as remarked 
above, considers that the granules which they enclose are 
liberated, and become the Ameelea-like bodies found in the 
perivisceral fluid. In a note at the end of his memoir, 
M. Lieberkiihn modifies his views with regard to the nature 
of the corpuscles, and allows that they may, perhaps, be 
analogous to those found in the perivisceral fluid of the 
naiads ; but still maintains that, at any rate, some of these 
bodies are young Gregarina, an opinion in which my own 
observations lead me to concur. 
I have made repeated examinations of the Gregarina Blat- 
tarum, in the hope that facts might be gained thence which 
would throw additional light on the subject. Encystation 
seems to take place much more rarely among the bilocular 
forms of Gregarina than in the unilocular species found in the 
earthworm and other Annelids. In fig.17, a cyst is represented 
enclosing two of the Gregarina Blattarum ; this is the only 
instance of the kind which I have met with in the Blatta. 
Stem figures certain bodies from the Blatta orientalis, which 
he calls the Pseudo-navicule of G. Blattarum. I have not 
met with these forms in my examination of the species. 
The blood-corpuscles of the insect itself have an appearance 
very similar to that which Stein figures. In fig. 14 are 
represented three very minute forms, which are not un- 
common in the intestine of Blatta. They measure re- 
spectively the >,,th, +,,th, and ;,,th of an inch in 
length, and, perhaps, may be the young of the Gregarina. 
* Miiller’s ‘ Archiv,’ 1845. 
