XVIII.-ON THE PRESERVATION OF EMBRYONIC MATERIALS AND 

 SMALL ORGANISMS, TOGETHER WITH HINTS UPON EMBED- 

 DING AND MOUNTING SECTIONS SERIALLY. 



By John A. Ryder. 



The question frequently asked of the investigator is, " How shall I 

 preserve the materials I may collect for you "? " This is a very important 

 question, because, unless eggs, embryos, or small portions of animals 

 which are to be studied microscopically by means of sections are prop- 

 erly iDrepared to begin with, it is often imi)0ssible for the embryologist 

 or histologist to get satisfactory results. And from personal expe- 

 rience I may remark that there is nothing more mortifying to the stu- 

 dent than to find a rare and valuable, or perhaps unique, specimen ruined 

 beyond repair by the preliminary "preparation" it has suffered at the 

 hands of persons either ignorant of proper i^reservative methods or in- 

 different in regard to their application. Alcohol, so universally used as 

 a preservative, can be made to yield splendid results if properly em- 

 ployed, but if applied without discrimination or an understanding of 

 the end in view, it may utterly ruin otherwise valuable materials if it is 

 desired to use them in the prosecution of delicate anatomical or histolog- 

 ical investigations. The shrunken, distorted, alcoholic specimens too 

 often seen in our museums are a reprojich to science, and it is high time 

 that more care was exercised in the preparation of such objects, as it 

 would not only be to the advantage of the systematist, but also to the 

 anatomist and histologist, to say nothing of the better appearance which 

 would be presented by such properly i)repared collections of zoological 

 materials. 



The directions which follow are meant to be useful to those seeking 

 information as to the proper mode of preparation to be applied to such 

 delicate objects as embryos or small soft organisms which are to be trans- 

 mitted to the National Museum in the best possible condition. Some 

 suggestions under the heading of alcohol are also intended to ai)i)ly to 

 the care and iireservation of large objects. 



Vessels. — As receptacles for specimens, vials,jars, or bottles with con- 

 veaieully wide mouths should be selected. Their form is of small conse- 

 quence, i)rovide<l they are sufficiently large to accommodate the object 

 without distorting it, and with a mouth wide enough to admit of the re- 

 moval of the specimen without injury after it has become indurated by 

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