THE SCOLEX POLYMORPHUS §31 
first summer of my work, as valuable only because they support 
the more satisfactory results obtained in the work of the follow- 
ing summer. A further discussion is, therefore, deferred until 
the results of the later work have been presented. 
Having been unsuccessful in the attempt to reduce the number 
of parasites by the process of starving, for as long a time as was 
available, if the sharks were to be used for any subsequent exper- 
iments, attention was directed at the beginning of my second 
summer’s work to the discovery of an effective method by which 
the sharks could be entirely freed of their cestode parasites. For 
this, I used the oil of male fern, one of the most powerful vermi- 
fuges used in human and veterinary practice. Following this 
practice, the dose of the oil was followed after an interval of from 
twenty-four to forty-eight hours by one of calomel. The manner 
of introducing these drugs into the stomach of a shark is 
explained in the earlier section of this paper where the general 
methods of work are given. In the tables upon the pages which 
follow will be found the detailed results obtained with the several 
lots of sharks treated in this manner. The necessary general 
explanations will be given in the discussion of the first table, 
while in the discussion of the subsequent tables I shall give only 
the facts which the tables show. 
TABLE 1 
5 sharks, captured before July 2, kept without food until July 22 
July 22, all sharks given 2 ec. each of oil of male fern 
July 23 the four surviving sharks given 1 ce. of calomel 
| 
~ NO. GIVEN SHARK | CONDITION OF CESTODES IN = 
Dare IN THIS SERIES | SHARK AT DEATH | SPIRAL VALVE ETDS 
= : H wes 
July: 23eee eee eon Nome | Dying | 6 C. lacinia- | 
| | tum found | 
| 
| | dead | 
Julie 2Ots eee | Nos. 2, 3, 4 Killed | No signs of Mucous mem- 
~ ? 3 d 
and 5 | | eestodes -— normal 
Table 1 shows the results obtained with five sharks which were 
starved from three to four weeks after capture and then given 
