380 University of California Publications in Zoology [Vol. 18 



is a fibrillar system closely associated with the motor organs and of 

 structures which may upon further investigation be found to be 

 nervous in their function. 



Probably the one paper which shows the most suggestive examples 

 is that by Maier (1903). The first striking example given by him is 

 that of Prorodon teres Ehrbg. In this ciliate there are to be found 

 lying close to the rows of basal granules of the cilia, fibers which are 

 called the myonemes. These connect wdth the fibrillar system around 

 the mouth. Such a condition recalls to one's mind immediately the 

 condition found in Diplodinium, where there is a definite circum- 

 esophageal nerve-fiber ring. A somewhat similar condition is sug- 

 gested in CJiilodon and Coleps, which also have definite fibrillar sys- 

 tems surrounding their gullets. In Stentor niger Ehrbg. there is 

 shown by Maier (1903) in his plate 4, figure 10&, definite end fibers 

 and basal fibers in connection with the basal granules of the undulat- 

 ing membrane. Also a system of myonemes is shown close to the basal 

 granules of the surface cilia. Similar structures are shown in plate 4, 

 figures 11 a-h, of Spirostomum amhiguum Ehrbg. The fibers of 

 Stylo nychia have been described in connection with the observations 

 of Englemann (1880). Maier (1903) also shows in Carchesium poly- 

 pinum Ehrbg. that the fibers are not in connection with the basal 

 granules but are very definite in the part of the bell near the attach- 

 ment of the stalk. 



A later work is that by Thon (1904) on Didinium nasutum O.F.M, 

 In this organism there is quite a complex system of fibrillae running 

 from another system of fibrillae around the mouth region to a point 

 under the nucleus. At this point of convergence Thon was unable to 

 distinguish any definite body to which the fibers were joined, for in 

 all well fed individuals the cytoplasm appeared undifferentiated. How- 

 ever, the fact that here are fibers in connection with the basal granules 

 and the fibrillar apparatus around the mouth and that these fibers tend 

 to converge to a point near the nucleus is very suggestive of a struc- 

 ture similar to that which has been described as a neuromotor appa- 

 ratus in Euplotes and Diplodinium. 



The most recent work which is suggestive of a neuromotor appa- 

 ratus is that of Braune (1913), He describes a system of fibrillae in 

 Ophryoscolex purhyngei, a form not distantly related to Diplodinium. 

 This system, he suggests, is composed of elastic supporting fibers, but 

 he seems to overlook the fact that the animal has an exoskeleton and 

 other structures which might serve as a skeleton and that, as Sharp 



