[4:3] INSTEUCTIONS FOR COLLECTING MOLLUSKS DALL. 



PRESERVATION OF SPECI]VrENS RESERVED FOR ANATOMICAL STUDY. 



In these days tlie treatment of specimens intended for sectionizing or 

 dissection has become an art in itself, as the wonderful results in mor- 

 phological work abundantly testify. It would be imi^ossible to go into 

 such matters in detail, but in order that the collector may make the 

 most of his oj)portunities the following brief directions have been kindly 

 famished by Prof. John A. Eyder, of the University of Pennsylvania. 



DIRECTIONS FOR PRESERVING SOFT PARTS OF MOLLUSCA FOR ANATOMICAL USE. 



Soft organisms should never be dropped into strong alcohol at once? 

 as the rapid extraction of the water of organization by the alcohol 

 shrinks the soft parts and distorts them. So, too, a too ]Drolonged stay 

 in too weak alcohol or spirits produces maceration or softening of the 

 soft parts. 



Fresh-water gastropods are best treated so as to kill them as quickly 

 as iDossible by drowning, which can be done by xDutting them in an air- 

 tight vessel and filling the latter comxDletely with water, so as to shut 

 off all the air. The result of this treatment, after twenty-four hours or 

 so, is that the soft parts after death are often more or less completely 

 extended from the shell; then gradual hardening maybe accomiDlished 

 in alcohol of one part alcohol (95 to 97 per cent) and two parts water, for 

 twenty-four liours, to be followed by further treatment with water and 

 strong alcohol, equal parts, for twenty-four hours more. Final harden- 

 ing may be accomplished in a mixture of two to four parts of alcoho. 

 (95 to 97 per cent) and water one part, using the last and strongest 

 mixture of alcohol to x)reserve the animals permanently. Soft organisms 

 thus treated with gradually increasing strengths of alcohol usually give 

 very excellent results, even for histological i:>urposes. Th e soj ourn of soft 

 organisms in weak alcohol, if continued for too long a time, tends to pro- 

 duce maceration and dissociation of the cells. In such cases it is best 

 to keep the jars in which the hardening and fixing is in progress in a 

 refrigerator (if such a convenience is accessible) at a temperature of 45° 

 to 55° for a day or two, or until the hardening has progressed far enough 

 to avoid the chances of injurious maceration. 



Paralyzing the larger moUusks with a 1 per cent solution of cocaine 

 gives good results, but is somewhat troublesome. Under its influence 

 gradual paralysis and death follow after one to three hours. The 

 organism after such treatment may be gradually hardened in a fully 

 extended condition in alcohol and water, gradually increasing the 

 strength of the successive alcoholic solutions as recommended above. 



A 1 x)er cent solution of chromic acid is most useful for bringing 

 out surface details for the naked-eye inspection of the surfaces of soft 

 parts, or their examination with low powers of the microscope. Organ- 

 isms may be subjected for twenty-four hours to its action, after which 

 they should be thoroughly well washed in running water for twenty- 



