SOME OBSERVATIONS ON ACINETARIA. 655 
Resoutts oF HARLIER WORKERS. 
The chief conclusions of the earlier workers can be sum- 
marised in tabular form :— 
Ciliate ts ea) 
Embryo. Nematocysts. 
Relations between 
| Proboscidiform and 
| Vermiform Individuals. 
| | 
Claparéde et Lachmann, P. is identical with V.. Saw two Trichocysts.| 
| 1855 (O. abietinum) (the proboscis being | kinds 
retracted) 
Strethill Wright, 1861 | (a) V. isa Protozoan) Saw one No 
(O.sertulariz) | parasite. kind mention. 
(b) P. buds V. 
Hincks, 1873 | P. buds V.; also | Not seen Not seen. 
| (O.pedicellatum) V. buds V. 
| | 
| | 
Koch, 1876 Contact between V. Notseen, but! No 
(O.pedunculatum | and P.,a process of | presumed to| mention. 
=pedicellatum | copulation resulting | give rise to | 
Hincks) in formation of ciliate’) P. and V. | 
| 
Fraipont, 1877 _V. is a developing P.| Not seen | Trichocysts. | 
(O.abietinum) | | 
Robin, 1879 P. not a true acine- | . | Not seen. 
tarian. 
V.a parasitic worm | 
Kent, 1882 Agrees with Fraipont) A | Possibly ex- 
| | ternal origin. 
Sand, 1901 Agrees with Fraipont) 
| | 
33 33 
9. CONCLUSIONS. 
Ophryodendron abietinum is to a large extent a true 
external parasite on its supperting hydroid, and the nemato- 
eysts which it contains are derived from its host on which it 
preys. In some cases I have seen the proboscidiform indi- 
vidual attack and suck small ciliates, and it is probable that 
the species of Ophryodendron which are attached to Crustacea 
obtain their nourishment entirely in this way. 
The study of the nuclei is much obscured by the presence 
