No. 400.] REACTIONS OF INFUSORIA TO CHEMICALS. 261 
sinistrally.) Furthermore, observation of its movements shows 
that it makes no attempt to do the impossible; instead of 
retaining any such position as the generalization calls for, it 
swims in spirals, a certain side of the animal being always 
toward the inside of the spiral; as Bütschli says, they “de- 
scribe rather narrow circles” (Bütschli, Flage//ata, p. 853). 
These facts, of the lack of symmetry of the organism, and its 
swimming in spirals, might be thought to be facts of capital 
importance for a decision as to whether it falls under Professor 
Loeb’s generalization or not; they are nowhere mentioned by 
Garrey. It is well known that the Infusoria are prevailingly 
unsymmetrical, so that it is quite impossible for most of them 
to fall within this generalization. An attempt to apply it to one 
of the Hypotricha, for example (see figure on p. 262), where not 
only the form of the body but the structure and distribution of 
the locomotor organs are strikingly unsymmetrical, would bring 
out the absurdity of the attempt, and observation of the actual 
movements of the organisms, as detailed in the Fifth of my 
Studies,! only accentuates the impossibility. It may be re- 
garded as axiomatic that a principle which requires the sym- 
metry of organisms cannot be applied to organisms that are - 
unsymmetrical. On this account I have not previously consid- 
ered it worth while, in my Studies on Reactions, etc., to show 
the relation of Professor Loeb’s well-known generalization to 
the movements of the prevailingly unsymmetrical Infusoria. 
The generalization was evidently made from a study of bilater- 
ally symmetrical animals, and may be of the greatest value for 
an interpretation of their activities; it is obviously inapplicable 
to unsymmetrical organisms. 
I have described the mechanism of the motor reactions of 
Chilomonas, on pp. 231—234 of the same number of the Amer- 
ican Journal of Physiology, as that in which Garrey’s paper 
appeared. Later study of their reactions in the production of 
the aggregations described by Garrey has convinced me that 
these aggregations are produced through the mechanism of the 
described motor reaction, in a manner exactly analogous to the 
production of the similar aggregations of Paramecium in weak 
1 Amer. Journ. of Phys., vol. iii, p. 249. 
