McIntosh, on the Gregariniform Parasite of Borlasia. 39 
carried out into a blunt point, and the membranous and 
structureless investment containing a number of minute 
granules, a nucleus and nucleolus. He adds that their 
motion is not very vivacious, but he has seen them moving in 
a straight line, and undergoing certain inflexions of the body. 
According to the next author, Frey and Leuckart also 
observed similar bodies in Nemertes. Max S. Schultze* gives 
a drawing and description of a very similar form w T hich he 
found in Planaria torva. He notes the greater translucency 
of the ends of the parasite, and says that he has not observed 
a copulation of two individuals to form a cyst and pseudo- 
naviculse, but figures some of the latter from a cyst which he 
supposes to belong to this species ; he makes no further 
remarks on their habits. The late Dr. G. Johnston mentions 
the occurrence of these bodies in his Borlasia olivacea 3 though 
he misinterpreted their nature, for he describes them as 
follows :f — “ When pressing a portion of the body ” (of the 
Borlasia) “ between the plates of glass, I have occasionally 
seen some bodies escape, of a curved fusiform shape, acute at 
both ends, and marked towards one of them with a pale 
circular spot. They have shown no signs of life, nor can I 
say what they are, though it has occurred to me that they 
may be embryo young, and that the worms may, in fact, be 
o vo -viviparous.” 
Whilst examining the structure of some Nemertians at present 
classed as different species of Borlasia, these curious grega- 
riniform bodies have frequently occurred. In Borlasia octo- 
culata and olivacea (which species, however, are not to be 
distinguished anatomically), and in long examples trans- 
mitted alive from South Devon by the kindness of Mr. Parfitt, 
and called by him Linens lactea , after Col. Montagu’s MSS., 
the ova and parasites were abundant, especially in the last 
mentioned. 
Towards the posterior end of the examples from Devon 
these gregariniform bodies occurred in swarms, and they 
were identical in all respects with those got in the Scotch speci- 
mens of the red and green varieties (PI. II, figs. 1 and 2). They 
consist of elongated sacs filled -with minutely granular con- 
tents, and having each a single, large, pale nucleus, measuring 
from txto th of an inch upwards, according to the bulk of the 
specimen. The nucleus shows slight markings when the 
parasite is first extruded, but a distinct nucleolus is not very 
apparent. In perfect specimens the snout is pale, very 
* ‘Beitrage zur Naturgeschichte der Turbellarien/ p. 70, tab. vii, figs. 
18—22. 
f ‘ Catalogue of British Worms/ edited by Dr. Baird, Appendix, p. 290. 
