ANNELID GENUS CAMBARINCOLA — HOFFMAN 279 



tipped scalpel or fragment of razor blade mounted in the end of a 

 matchstick. In ver}'- large specimens (over 5.0 mm. long when pre- 

 served), it is often difficult to observe the reproductive s3^stem in whole 

 mounts, and with a little practice it is easy to bisect the body between 

 segments VI and VII, and then dissect out the male organs to be 

 dehydrated and cleared separately. 



Processing can easily be done in small glass dishes or similar con- 

 tainers. For ordinary whole mounts it is satisfactory to take speci- 

 mens from the collecting jar into 95 percent alcohol, then through one 

 change of absolute alcohol into clove oil. About 10 minutes in each 

 stage is sufficient. All the material from each collection can be car- 

 ried along in the same container, the fluids being added from dropping 

 bottles and removed by a fine-tipped pipette. 



Specimens may be mounted singh^ on each slide, or all of those which 

 look alike mounted together, although this sometimes results in 

 several species on a slide. I have used fairly thick balsam in a drop 

 at the middle of the slide, subsequently spread out by the addition of 

 a little clove oil around its base. Cleared specimens are removed 

 from the clove oil with forceps or a bent needle and placed in the 

 balsam, with, specimens about equally divided according to which side 

 is uppermost (to insure having at least one with the reproductive 

 systems on the upper side). If dissected heads are involved, they 

 can be spread in thicker balsam with the jaws uppermost and the 

 coverslip applied quickly. 



Slides in the Holt collection are prepared with the mount in the 

 middle, leaving space for the catalog number and/or locality data 

 label at the right end, and for an eventual determination label at the 

 left. Following identification, an index card may be made out with 

 the species name, number, and collection data, and filed in systamatic 

 order. Since a slide may contain several species, it is preferable that 

 slides be stored in simple numerical order. 



In the study of specimens, the use of medium high power magnifica- 

 tion is mandatory, with a range of from about 60 to GOO diameters 

 most desirable. Most of the present study has been made with a 

 fluorite oil immersion objective, 40X,N.A, 100, corrected to a working 

 distance of 1.5 mm., permitting the examination of relatively thick 

 preparations maccessible to the ordinary high dry and oil-immersion 

 objectives. 



Drawings are easily made wdth a camera lucida attachment, and 

 measurements with a calibrated ocular micrometer. 



In many instances, the student will find it impossible to determine 

 single specimens with confidence. Contents of the gut may be so 

 opaque as to conceal the sex organs, or the jaws may be in an un- 

 satisfactory position. Specimens preserved in weak alcohol may be 



