JOURNAL OF MICROSCOPICAL SCIENCE. 



DESCRIPTION OF PLATES II AND III. 



Illustrating M. N. Pringsheim's Translation, on the Chroni- 

 spores or Chronizoospores of Hydrodictyon, and on some 

 Analogous Reproductive Bodies. 



Note. — All the figures represent objects equally magnified, that is to say, 

 about 582 diameters. 



Fig. 

 1. — Chronizoospores of Hydrodiciyon. Some {a) are seen immediately 

 after their escape from the parent-cells (which are utricles from 

 an old Hydrodictyon), and during their motility; the others 

 {b and c) after they become motionless. 

 2. — Chronizoospores resuscitated, and already grown in various ways. 

 Having been kept dry for eight minutes, they were then placed in 

 water, and were not figured until they had been immersed for four 

 minutes. One of these bodies, b, is already empty, and its cavity 

 can be seen through the superior opening c, which has given pas- 

 sage to the herniary sac spoken of above. 

 3. — Other chronispores, seen at difi'erent moments during the progress of 



division of their plastic contents. 

 4 — 9. — Chronizoospores further enlarged, and all opening to allow the in- 

 ternal dilated sac to escape. In one of them (fig. 8) the four 

 parts of the plasma can be perfectly recognised as so many new 

 zoospores. In another (fig. 9) the herniary sac is ruptured, and 

 three zoospores have already escaped. 



10 and 11. — Chronizoospores which have grown and burst ; the zoospores 

 that they have engendered are still in one of them (fig. 10), all 

 enclosed, to the number of five, within the internal utricle; in the 

 other three only remain. These secondary zoospores have already 

 returned to a slate of repose, and begin to assume a polyhedral 

 form. 



12. — Young polyhedrons, derived from the ulterior development of 

 zoospores issuing from chronizoospores. 



13 — 17. — Adult polyhedrons. 



18. — A Polyhedron, the plastic contents of which, adhering to the internal 

 wall, are already transformed into large zoospores. 



19 and 20. — polyhedrons, whose internal tunics are throwing off the ex- 

 ternal membrane, which is detached like a cuticle. One of these 

 bodies (fig. 19) is seen a few minutes after the rupture of its 

 envelope ; the other (fig. 20) from forty-eight to sixty hours after 

 the same phenomenon. In the last, large zoospores are formed ; 

 microzoospores are, on the contrary, produced in the other. 



