Marine Worms as Microscopical Objects. By H. C. Sorby. 5 



bad results. They were nearly as bad in the case of Terebella and 

 some other genera. 



This last year I had made up my mind to devote much attention 

 to the study of suchlike peculiarities in the chemistry of marine 

 animals ; but my time was too much taken up in preparing them as 

 museum specimens, so as to show, as I hope permanently, all their 

 beautiful natural colours. I, however, did try some experiments, 

 which serve to throw light on the subject of this paper, and to show 

 that in some cases decomposition may be much modified, not only by 

 the presence or absence of septic organisms, but by more or less 

 slight changes in the chemical constitution of the decomposing sub- 

 stances. My experiments were made with the mollusc Phyllina, 

 having a small internal shell. Some were kept in strong glycerin, 

 some in alcohol diluted with half its volume of water, and some in 

 a 4 per cent, solution of formalin. After remaining three months, 

 they were well soaked in water to remove the reagents, and a newly 

 collected specimen, and one of each of those named, were kept sepa- 

 rately in fresh-water, and the changes carefully watched and recorded. 

 To my surprise I found that long treatment with alcohol did not in 

 any way retard septic decomposition, but previous treatment with a 4 per 

 cent, solution of formalin retarded it so much that I began to think 

 that none would occur. The three months' action of strong glycerin 

 also much retarded decomposition, either by altering or dissolving out 

 some constituent specially liable to change ; and even keeping in 

 glycerin for only eight hours had a very marked effect, and this in some 

 measure explains why it is useful in preparing marine worms. In 

 illustration of the different results in the case of different species, I 

 may say that some kinds of Nereis do not change colour on keeping 

 when mounted in Canada balsam, whereas another species turned to a 

 dark brown, as though it contained some substance absent from the 

 others. If there is such a considerable difference in different species of 

 the same genus, it is not surprising that the effect of glycerin should 

 vary much owing to some difference in the nature of the constituents. 

 Though this is disappointing when we desire to prepare good micro- 

 scopical objects, yet it is interesting from a chemical and biological 

 point of view. I have also found that there may be considerable dif- 

 ference in the effect of poisons and other reagents on the same species 

 from different localities, or even on different individuals from the same 

 place ; and also that the length of time they have been kept alive 

 after being collected is an important element. 



In conclusii in, I may say that though I greatly regret my inability 

 to explain and overcume some of these peculiar difficulties, yet the 

 specimens exhibited clearly s-how that, by the method described in this 

 paper, it is possible to obtain excellent results ; and I hope that what 

 I have said may prove useful in dealing with other animals, especially 

 when naturally free from salt, the presence of which is so great a diffi- 

 culty in the case of marine worms, with which alone I have so far 

 experimented. 



