364 WM. L. TOWER, 



with proper care, it was possible to keep the worms alive for 2, 

 3 or 4, and sometimes even for 5 days: 



hydrant water .... 100 ccm 



egg albumen (fresh) . . 10 g 



pepsin 2 g 



cane sugar 2 g 



prepared beef (Bovox) . . 5 g 

 The worms, only one or two in a dish, were placed in this mixture 

 freshly made, of which 100 ccm was allowed to each worm. They 

 were kept in the laboratory in the dark, no attention being paid to 

 temperature, for it was found that the temperature between certain 

 limits (10° C to 30" C) was not a very important factor, although 

 about 17 " C seemed to be the most favorable. Every morning the 

 worms were placed in a freshly made mixture, care being taken to 

 clean thoroughly the dishes before the fresh culture-solution was put 

 into them. I was unable to use successfully the methods given by 

 LöNNBERG (1892) for keeping Cestodes alive in the laboratory. 



3. Methods of Fixing and Staining the Nervous Tissues. 



The chrome-osmium-silver methods of Golgi, both the slow and 

 the rapid, with various modifications proposed by recent writers were 

 the ones chiefly tried, but always without success. I was unable to 

 determine the cause of failure. In nearly all cases there was, however, 

 a good impregnatiou of the dorso-ventral, longitudinal, and transverse 

 muscle fibres. The plan proposed by Strong (1895) of using formic 

 aldehyde in place of osmic acid was also unsuccessful, although this 

 combination gave good results for other Invertebrates (e. g. Echino- 

 rhynchus), used in check experiments. 



Various modifications of the gold-chloride methods were not more 

 successful than the Golgi methods. 



With the axis-cylinder stains the results were likewise unsatis- 

 factory, although better than with the Golgi and gold-chloride methods. 

 The method of Nissl (1886) gave a good stain of the lateral nerve, 

 and by its use many of the other nerves could be traced after one 

 had learned where to look for them ; but this stain did not difierentiate 

 nervous tissue from muscular and connective tissue. The method of 

 Alt (1892) was useless for my purpose. Rehm's (1892) method 

 was also unsatisfactory in that it did not separate nervous from 

 muscular and connective tissue. Wolter's method was the most 

 satisfactory for staining the axis cylinder, but it did not dif- 



