178 TWELFTH ANNUAL REPORT. 



frequentl}^ brings up animals quite different from those collected 

 by the towing net at the surface. This consists of a large bottle 

 weighted by a suitable bit of lead or iron and fitted with a tight- 

 fitting cork or wooden stopple. The stopple is attached to the line 

 fastened at the neck of the bottle iu such a way that a sudden 

 twitch of the cord opens the bottle when it has sunk to the re- 

 quired depth. Another method, when one does not object to ming- 

 ling forms from all depths, is to lower a net weighted with a heavy 

 ring to the bottom, there agitating it slightly and drawing it vertical- 

 ly upward. This serves in a poor way in the place of a dredge and 

 will secure a larger gathering than the dipping bottle, and is quite 

 as easily rigged. The collections secured in either of the above ways 

 are placed in large shallow porcelain plates and, the microscope be- 

 ing ready, the study may begin. With a rather large hand-mag- 

 nifier, with which, however, the student will soon be able to dis- 

 pense entirely, the various forms seen swimming or creeping or 

 springing about are scanned, chiefly for the purpose of noting 

 their motions. The little black, brown or yellow imps springing 

 on the surface are rapidly skimmed off as hindrances, and (if the 

 student is interested in the Podurte; consigned to a bottle of spirits. 

 Next a great Belostoma, Corixa, Water-skater, Ranatra, or Dysti- 

 cus requires the same treatment. Perhaps a half dozen '"whirligig- 

 beetle" require more time to dispose of, and then a careful remov- 

 al of the dragon-fly larvse and "water-tigers" leaves the coast com- 

 paratively clear save for sand-fleas and dipterous larv^ which must 

 be endured as necessary evils. 



With a narrow slip of paper folded trough-wise the desired animal 

 is captured by a quick movement and the water permitted to drain 

 off, when the specimen is placed on the object-carrier, and a square 

 cover glass, one corner of which has been armed with a bit of wax, 

 is placed over the animal and then adjusted so as to give the re- 

 quisite amount of pressure to quiet its restless motions. The slip 

 of paper is, iu every way, more convenient than a dipping tube and 

 avoids flooding the object-carrier. With a half-inch objective and 

 suitable eye-piece the whole animal is drawn iu as natural a posi- 

 tion as possible, either with the aid of a camera or free hand, by the 

 assistance of careful measurements and a given scale. A one-fifth 

 inch objective is now substituted and all possible details added. If 

 any dissections are necessary, the cover glass may be removed, the 

 slide placed upon a slip of black paper and the parts separated as 

 far as possible by the aid of a watchmaker's glass or dissecting 

 microscope. 



