Method of Preparing Delicate Organisms. By E. Lovett. 787 



The cell having been duly constructed, I scrape round the 

 inner edge with a pointed knife, which removes any foreign matter 

 from the side of the cell and clears away any of the cement which 

 may show itself on the inner angle ; after cleaning carefully with 

 a dry cloth, the cell is ready for the reception of the object. Before 

 proceeding further with this stage, I will describe the preparation 

 of the object about to be mounted. 



I have already referred to the medium used in this work, which 

 is on the basis of what is known as Haentsche's fluid ; namely, a 

 composition of 3 parts absolute alcohol, 2 parts pure glycerine, 

 and 1 part distilled water. I say it is on this basis, for it is 

 necessary to alter the density for certain objects, and I never think 

 of using these proportions for mounting, but simply for preparing 

 for that operation. 



Now as regards the necessity for altering the density of the 

 above formula, I find that the proportions mentioned answer very 

 well for parts of the young of Crustacea ; for zooea ; for young 

 fish, if more than three or four days old ; for nearly all hard ova ; 

 for young Echinoderms ; for most insects, and for plants excepting 

 the most delicate tissues : but I have found that it often crushes 

 such organisms as the delicate ova of some fishes, the ova of the 

 Nudibranch Mollusca and such fragile substances ; so that I reduce 

 the glycerine, and in some cases make the proportions 3 parts 

 distilled water to 1 part each of alcohol and glycerine ; but as 

 experience is the best master, it is always as well to find out by 

 practice the proportions best suited to the particular class of 

 object under consideration. 



Should the fluid be too dense, the objects will show it by 

 becoming crushed ; should, on the other hand, the fluid be too 

 weak to preserve the specimens properly, a tendency to disintegrate 

 and part company will be noticed on their part. 



Having provided a number of small corked glass tubes, with 

 numbers on the corks for the purpose of keeping the particulars of 

 their contents in a book of reference — for I must here urge upon 

 marine zoologists the value of keeping a proper record of the date 

 and locality as well as the names of their specimens, for much 

 depends on this — having then prepared the tabes of fluid, the 

 specimens should be dropped in alive, or at any rate in a per- 

 fectly fresh condition ; this is absolutely necessary with marine 

 organisms, where the decomposition and breaking-up of minute 

 bodies takes place in an incredibly short space of time after death. 

 In shore work or in dredging or trawling a number of these tubes 

 should be at hand, for, however conversant the naturalist may be 

 with the objects of his search, it would be most rash to place all 

 his specimens into one receptacle, with the intention of sorting 

 them out at a more convenient season. 



