1880.] MR, H. N. MOSELEY ON SOME CORALS. 25 



Jena'; but it is only lately that he has succeeded in preparing sections 

 of corals so perfect as those exhibited. 



*' The method is as follows :— The corals with all their soft parts in 

 situ having been hardened in absolute alcohol, are placed in a solution 

 of Canada balsam in ether, or in gum-sandarach in alcohol, or, better 

 still, of copal in chloroform. After they have become thoroughly 

 permeated by the resinous solutions, they are taken out and dried 

 slowly until the masses become perfectly hard. The hard masses cau 

 now be cut into sections with a fine saw, and then rubbed down in 

 the usual manner on a whetstone. The sections can be stained with 

 carmine after being thus prepared, even without the removal of the 

 resin ; but usually the tissues are stained in mass before being placed 

 in the resinous solutions. All the soft parts thus become deeply 

 tinged, and stand out in well-marked relief. The sections can then 

 be mounted in fresh Canada balsam^. The sections received from Dr. 

 von Koch certainly show a good deal which could not have been exhi- 

 bited before ; and they are interesting, not only as illustrating a new 

 point in the anatomy of corals, but because the method by which they 

 are prepared seems to me to be likely to yield valuable results in the 

 case of many other questions of microscopic investigation. It will be 

 quite easy, for instance, by this means to prepare microscopic sections 

 of injected bone in which the injected capillaries will be shown in their 

 relations to the Haversian systems. Sections also could thus be pre- 

 pared of the internal ear in which the hard and soft tissues will be pre- 

 served together, and the latter would not have been subjected to the 

 deleterious action of the acids which are usually employed to decalcify 

 the cochlea before it can be sliced with a razor. Sections through 

 the undecalcified arms of starfish or crinoids prepared by this method 

 could not but yield most interesting results, and similarly in the case 

 of those Bryozoa which have a calcareous and opaque skeleton. I 

 have sent specimens of Millepora and other hydroid corals to Dr. 

 von Koch, and await with great interest the sections which he has 

 promised to cut from these. It is even possible that by this means 

 instructive sections for museum purposes of whole starfish or other 

 animals might be cut and mounted on glass. 



" It has hitherto been supposed that the wall of all Madreporarian 

 coralla is developed within the mesodermal layer of the wall of soft 

 tissue of the animal. If this were the case, it would be expected that 

 a simple layer of mesoderm and ectoderm would be found lying 

 externally to the wall of hard tissue in transverse sections of a com- 

 plete simple coral. Dr. von Koch, however, in his sections finds 

 that this is not the case, but that there exist externally to the calca- 

 reous wall what he believes to be the continuation of the mesenteries, 

 and also a series of cavities which are the continuation of the interme- 

 senterial spaces. He thus comes to the conclusion that the wall of the 

 coral-cup is not developed, as supposed, by calcification of the middle 



' Anatomie der Orgel-Koralle (Tuhipora hemprichii). Dissertation zur Erlan- 

 gung der venia docendi. Von Dr. G. von Kocli. Jena, 1874. 



^ For a detailed account of Dr. Ton Koch's process see the ' Zoologischer 

 Aiizeiger,' Jahrg. 1, p. 36. 



