212 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and it is wise to be guided by local boatmen, who will have a more 

 intimate knowledge of the nature of the bottom than a chance visitor 

 can hope to possess even with the aid of a chart. The sooner the 

 hydroids are killed and fixed after collecting the better, as once the sea- 

 water becomes stale the hydroids are with difficulty prepared in a suffici- 

 ently expanded condition. It answers best to divide the gathering by 

 separating the Gymnoblastea from the Calyptoblastea, as the former can 

 be best prepared by killing without the intervention of a narcotic. 

 Before killing, the polyparies should be cleaned as much as possible 

 from adherent matter, by gently brushing with a soft camel-hair pencil. 

 Placed in clean fresh sea-water they quicklv recover from the cleansing 

 process, and are ready for narcotization and killing. With the Gymno- 

 blastea it suffices to spray over the colony the killing and fixing agent 

 when the tentacles are well extended. Lang's fluid is a good and quick 

 acting solution, and so also is picric acid ; Hermann's solution is 

 excellent for small specimens, but with large colonies and robust forms 

 killing is not sufficiently rapid to prevent considerable retraction of the 

 tentacles. Cocaine hydrochlorate is probably the most generally useful 

 narcotizer for the Calyptoblastic forms. A few drops of a 1 p.c. solution 

 are added to a colony in a watch-glass and time allowed for it to become 

 accustomed to the narcotizer before adding a further dose. When the 

 tentacles fail to respond to the prick of a needle killing may take place. 

 If it is necessary to store the material before staining and mounting, 

 70 p.c. alcohol seems the most satisfactory medium. Material stored in 

 formalin does not always stain satisfactorily. Hydroids intended for 

 mounting cm naturel may, of course, lie quite well stored in 5 p.c. 

 formalin. It should be observed that specimens intended for mounting 

 unstained require killing with an agent that leaves the ccenosarc in its 

 natural condition — i.e. without rendering it opaque. If osmic acid is 

 used, either alone or as in Hermann's solution, clearing afterwards with 

 hydrogen peroxide, or potassium ferrocyanide, is certainly desirable. 

 For permanently mounting small species, or representative portions of 

 the trophosome, excavated glass slips are very convenient, more especially 

 the oval excavations. A ring of old gold size is first run round the 

 edge of the cell and allowed to become thoroughly tacky. The object is 

 then placed in the cell with a suitable amount of 2h p.c. formalin 

 solution, the cover-glass placed on and thoroughly pressed into contact 

 with the ring of gold size. Successive coats of gold size are then 

 applied to finish. 



Cultivations of Adult Animal Tissues in vitro.* — A. J. Walton 

 describes his work upon the cultivation of tissues, such as spleen, thyroid, 

 kidney, testicle, and liver from the adult rabbit. The article is illus- 

 trated with plates showing the nature of growth of these organs on 

 artificial culture. The technique followed is that practised by Carrel, 

 and is described in detail, particulars as to the preparation of the animal, 

 the apparatus necessary, the method of removing tissues and plasma and 

 of preparing the cultures being concisely stated. Throughout the whole 

 experiment the utmost sterility is observed, every step being carried out 



* Journ. Path, and Bact., xviii. (1914) pp. 319-24. 



