1 882.] in the Zoological Station in Naples. 773 



ing alcoholic preparations, such as the tearing asunder of fragile 

 tissues caused by the violent osmosis; swelling, the effects of 

 which cannot always be fully obliterated by again transferring to 

 alcohol, and maceration, which is liable to result where objects 

 are left for a considerable time in the staining liquid, may all be 

 avoided by using alcoholic solutions. Objects once successfully 

 hardened may be left in such solutions for any required time, 

 and when sufficiently stained, be washed in alcohol of a corre- 

 sponding strength, and then passed through the higher grades 

 without being exposed to water from first to last. As a rule, 

 alcoholic dyes work quickly, and give far more satisfactory results 

 than can be obtained with other media. They penetrate objects 

 more readily, and thus give a more uniform coloring where ob- 

 jects are immersed in toto. Even chitinous envelopes are seldom 

 able to prevent the action of these fluids. 



It is not, however, to be denied that non-alcoholic dyes may 

 often do excellent work, and in certain cases, even better than can 

 be otherwise obtained. In the case of the Turbellaria, Dr. Lang 

 has found picro-carmine to be one of the best staining agents, 

 and this has been my experience with Dicyemidae. As Dr. 

 Mayer has remarked, the swelling caused by aqueous staining 

 fluids is not always an evil, but precisely what is required by 

 some objects after particular methods of treatment. 



From experiments recently made, Dr. Mayer has fo ind that 

 dyes containing a high percentage of alcohol, stain more diffusely 

 than those of weaker grades, from which he infers that strong 

 alcohol robs, to a certain extent, the tissues of their selective 

 power, and renders them more or less equally receptive of color- 

 ing matter. 



1. Kleincnbcrg 's Hematoxylin. 1 — 1. To a saturated solution of 

 chloride of calcium 2 in 70 per cent, alcohol, add a little alum and 



Per cent, alcohol. 



3- At time of using pour into No. 2 as many drops of a con- 



