Scheuring also found that the motility of trout milt lasts as long as 90 minutes, intensive 

 motility up to 30 minutes.) 



The relatively small and flaccid eggs, when stripped, will swell within a few minutes. 

 The spermatozoids enters the eggs through a small opening, the micropyle. After the absorp- 

 tion of water, this opening is blocked and a fertilization is no longer possible. As a 

 matter of fact, "dry" fertilization gives extraordinarily good results, although — or rather 

 because — it is an unnatural method. Almost every egg becomes fertilized by this method. 



In German trout fisheries the "dry^' stripping method is almost exclusively in use, 

 although I have found "wet" stripping occasionally in the Central Mountain regions. If 

 quickly done it gives just as good results as "dry" stripping, which certainly goes to 

 prove that elaborate and much detailed directions for stripping — quite often given — are 

 really superfluous. 



7^ith the sticky eggs of certain fishes (pikes) the "wet" method has many advantages, 

 according to the experienct^s of breeders and I agree with them upon the basis of my own 

 experiences. The reason for it may lie in the fact that by "dry" stripping of pike, the 

 spermatozoids become enveloped in the slimy exudates and thus deprive them of their motility. 



I had success here with the "wet" method by gathering the sperma of a number of males 

 in a water-filled bowl, into which I then stripped the eggs. The procedure in both methods 

 is otherivise alike as seen from the following description. 



Before beginning with the stripping, one has to have handy, at least, two dry and 

 clean enameled bowls of about 25 to 30 centimeters diameter. Also some cloths, some 

 chicken or goose feathers and a pair of egg tweezers. 



The female is best caught by slowly gripping her with both hands. The neophyte in 

 this business should use a towel or cloth until some practice is acquired. The fish is to 

 be caught by the head — to be kept upward at all times. Ti'ater clinging to the fish is 

 blotted with the cloth. Then turn the fish with belly upward, the cloth to cover the 

 head only but not the body. Hold the fish in the left hand so that the tail hangs down, 

 closely to the rim of the bowl. The biolent resistance of the fish ceases after a few 

 seconds and it will remain limp in the operator's hands. 



Fig. 2^, Stripping of a Female Trout, 



The stripping is done with the thumb of the free hand which massages the eggs out, 

 so to speak, by following the middle line of the belly. In order to ease this process for 

 the fish, one should begin to strip first the eggs from the rear end, coming slowly nearer 



107 



