ZOOLOGY: C. E. STRINGER 
691 
1 Cf. Warburg, O., Ergehn. Physiol, 14, 1914, (313). 
2 Haas, A. R., Science, New York, N. S., 44, 1916, (105). 
3 This did not occur with low concentrations of these substances. 
4 Osterhout, W. J. V., Science, New York, N. S., 35, 1912, (112); Bot. Gaz., Chicago, 61, 
1916, (148). The determinations referred to in this paper were made in part by Professor 
Osterhout and in part by me. 
5 Richards, H. M., Ann. Bot., Oxford, 10, 1896, (551). C^apek, F., Biochemie der Pjlan- 
zen, 2, 1905, (400 ff.). 
THE MEANS OF LOCOMOTION IN PLANARIANS 
By Caroline E. Stringer 
ZOOLOGICAL LABORATORY. RAECLIFFE COLLEGEi 
Communicated by G. H. Parker, October 29, 1917 
The ordinary locomotion of fresh-water planarians is of two types, 
gliding and crawling. True swimming movements are also used by the 
marine form, Bdelloura. When gliding, the planarian slips smoothly 
and evenly over some supporting surface, with little or no apparent 
muscular eflort. It has been believed generally that this form of loco- 
motion results chiefly, or even entirely from the beating of ventral 
cilia. Crawlihg is accomplished through conspicuous muscular 
contractions. 
Contrary to the opinion frequently expressed in papers on the his- 
tology of planarians, all speci'es which I have so far examined have been 
found to be entirely covered externally with cilia. The cilia on the 
lateral margins of the anterior region beat in response to very weak 
stimuli. The ciHa over most of the dorsal surface, on the lateral mar- 
gins other than the head region, and on the ventral surface are usually 
inactive, except when subjected to strong mechanical or chemical 
stimuli. Long sensory hairs occur not only in the head region, but 
along the lateral margins and over the dorsal surface, as well. Tests 
with powdered carmine show that the ventral cilia of a gliding pla- 
narian are not beating during normal locomotion. On the other hand, 
a planarian when gliding on the under side of the surface him of water, 
so that the hght falls upon its foot at an angle of about 45 degrees, and 
is reflected to the eye shows delicate muscular waves. 
To determine whether locomotion could be accomplished either by 
the beating of cilia, or by muscular activity alone, a series of tests were 
made with solutions for the purpose of finding one that would inhibit 
muscular activity and leave the cilia free to beat normally, and another 
that would check ciliary action without interfering with muscular con- 
tractility. In either case, the animal mtiist remain in all other ways as 
