Opalina. 333 
Boveri (1900) discusses the evolution of centrosomes and mito- 
tic spindle, illustrating from the nucleus of O. caudata one stage in 
this hypothetical evolution. He notes (p. 185) that the division of 
the nuclei and the division of the cytoplasm are relatively inde- 
pendent phenomena in the multinucleated Opalinae, and (p. 187) that, 
in the binucleated Opalinae, the binucleated condition is apparent, 
not real, being due to delay in division of the body after the division 
of the nuclei. 
Pirrer (1900) opposes Lors & BupGeErt’s (1897) statement that 
the anodic reaction of Opalina, differing from all other. Ciliata, is 
due to its always being experimented upon in sodium chloride so- 
lution. He found that when Opalina and Balantidium from the same 
host were experimented upon together in the same culture, Opalina 
showed anodic reaction while the reaction of Balantidium was ka- 
thodic. . 
Lane (1901) classes Opalina in the suborder Hymenostomidae 
among the Ciliata holotricha. In the same suborder, which he cha- 
racterizes as having the mouth always open and as possessing an 
undulating membrane, he places Colpoda, Colpidium, Urocentrum, Para- 
maecium. Anoplophrya, Frontonia, Leucophrys, Ophryoglena, and Pleuro- 
nema. [Opalina of course has no undulating membrane and no 
mouth. | 
Dorney (1901) gives a suscinct account of the structure and 
development of Opalina, [as liable to mislead, may be noted the 
statements that] the ectoplasma is homogeneous and that the endo- 
plasma is granulated; and, [as a probable error] quoted from PrzEs- 
MYCKI, the statement that the animals in the cysts often divide into 
several offspring. 
Daue (1901) refers to Verworn’s observation of positive galvano- 
taxis in O. ranarum; he notes that this species is found in the anterior 
end of the rectum of the frog; he describes experiments upon its 
chemotaxis and galvanotaxis which he summarizes as follows — 
Alkalinated Neutralized Acidified 
Chemotaxis Attraction to acid Attraction to acid Attraction to alkali 
Repulsion from alkali Repulsion from alkali Repulsion from acid 
Galvanotaxis Collects at anode. Collects at anode Collects at kathode; 
he describes the normal movements of the cilia and their reaction 
to chemical and electrical stimuli; he describes the modification of 
galvanotaxis by changes in concentration of the media; and _ finally 
considers theoretically the phenomena. 
