118 Capt. G. E. II. Barrett- Hamilton on the 



stages of development " (p. IT)!)). FiirtluT, altlioui^li "a 

 return to fresh wafi'r is essential for the completion of repro- 

 (luetion, fi>r it has been shovvTi that salt water prevents the 

 development of the ova .... descent to the sea is not 

 necessary for the development of the genitalia .... since 

 experiments show that fish, when properly fed, may develop 

 their genitalia without leaving fresh water" (p. 170). 



As regards the fast of the salmon while in fresh water, the 

 rejioit is strong that not only does the salmon abstain from 

 feeding while in fresh water, at least before spawning, but it 

 cannot feed, since its alimentary canal is in a state of desqua- 

 mative catarrh. The observations of Miescher Ruesch * are 

 thus confirmed. Not only is food, as a rule, absent from the 

 stomach-cavity, but the " slight acidity and small digestive 

 power of the extracts of the gastric mucous membrane 

 recorded lead to the conclusion that the fish both in the 

 estuaries and in the rivers were in a fasting condition " 

 (p. 32). 



The assertion that the alimentary canal ot the breeding 

 salmon is in a state of acute desquamative catarrh, although 

 directly denied by Dr. Alex. Brown f, afforded a very im- 

 portant support to my theory. It appears, however, that on 

 this point alone the observations of the writer of the report 

 are erroneous, and Dr. J. K. Barton J has shown that the 

 appearance of catarrh is due to the method of preparation 

 of the specimens. This, however, does not affect the fact 

 that the salmon while in fresh water is undergoing a physio- 

 logical fasl§, that its gastric juice is weak in pi-ptogenic power 

 and contains a decreased quantity of hydrochloric acid, and 

 that consequently the number of bacteria in the digestive 

 tract is increased. Tiiis disinclination or, it may be, inability 

 to feed, accompanied as it is by discoloration and general 

 failure of condition, may in fact be itself regarded as patho- 

 logical, or, at all events, as reminiscent of a former patho- 

 logical condition. Xor must it be forgotten that what is 

 pathological in one animal may be normal in ant)ther, as I 

 am ren inded by Mr. Headley ||. 



Such is a brief resume of a most interesting series of papers. 



• ' Fisherei-Ausstellung zu Berlin.' 1880. 



t Zool. Anz. 1898, xxi. pp. •'',14, r,17 521. 



I .Tuurn. Anat. .'t Tlivs., April lUUO. 



§ As Sir H. Maxwell says (,' Meiiioiies of tlie Months,' 2nd series) : — 

 " Even a physiolcfricfil ftist is compatible with ucca.-ional irregular ini- 

 Tiulses of appetite, which exactly corresponds with the well-known capri- 

 ciousne^s of salmon in taking any lure.' 



It The connexion between disease and variation in general is, of course, 

 Uot a new one. See IJutesou, op. cit. p. 74. 



