192 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



branchial cartilages of the shad. A 5 per cent, solution it was found 

 would rapidly dissolve the dermal, neural * and muscular tissues, leav- 

 ing only the rudimentary, aponeurotic membranes and matrices of fasciae 

 between the muscular segments and the notochordal sheath. The head 

 cartilages remained undestroyed and could afterwards be stained. The 

 method is useful, however, only where fresh material is at hand, as it is 

 almost impossible to mount a specimen satisfactorily for permanent prep- 

 aration. In staining, it is desirable to wash out the alkali as much as 

 possible, and afterwards to investigate the arrangement of the cartilages 

 of the skeleton under gentle pressure under a Fol's compressor. 



VII.— METHODS OF HANDLING WHITE PERCH OVA. 



The egg of the white perch is notoriously adhesive, and for this reason 

 is one of the most troublesome to deal with practically. The eggs were 

 taken upon cotton yarn, which was drawn up through a funnel, into which 

 the eggs aud milt had been squeezed from the spawning fish. The cord, 

 covered with the adhering eggs, was then wrapped upon a wooden reel 

 and sent under cover of damp cloths to the central station, where they 

 arrived in fine condition, almost every egg being impregnated. This 

 system, devised and carried out under the superintendence of Colonel 

 McDonald, was really another adaptation of the dry method of carrying 

 the ova of the shad. 



After reaching the central station, the cotton cord, with the adhering 

 eggs, was cut iuto lengths of 10 to 12 inches and suspended in the glass 

 hatching jars. The development progressed normally as long as not 

 interfered with by the growth of Baprolegnious fungus. There being 

 no attrition between eggs, as amongst shad ova, when incubated in the 

 jar, fungus soon established itself, and grew until 'the whole brood was 

 practically destroyed. Another mode was to introduce the wooden reel, 

 with the eggs adhering to the cord, into a wide aquarium. These also 

 were attacked by fungus, but slightly more favorable results were ob- 

 tained. With the water at 5S° F. to 00° F., the ova hatched out in six 

 days. The water in the jars, for some of the time, stood at 51° to 55° F. ? 

 and rose but little above this point. 



The use of narrow strips of glass or mica might, it seems to the 

 writer, be used to advantage, or even glass plates would be convenient, 

 upon which the eggs might be allowed to adhere. It was discovered 

 this spring by the writer that where the eggs were allowed to stick to 

 the string in several layers, the uppermost strata seemed to smother 

 or prevent the respiration of the lowermost layers, which were killed in 

 consequence. This is opposed to the experience of Mr. Clark with the 

 Atlantic herring, and also to thatof Oapt. Z. L. Tanner with the Branch 

 herring. Both of these experimenters found that great masses of the 

 eggs would hatch with scarcely any loss, although it was scarcely pos- 

 sible to understand how it was possible that there should be any circu- 

 lation of fresh water through such large clumps of adherent ova. 



