REPORT ON THE ACTINIARIA. 19 



no use. Notwithstanding, I undertook to work it out, and extended my operations over 

 nearly all the specimens, because, according to my opinion, Zoology ought never to take up 

 a point of view, the effect of which would be that she must remain excluded from a large 

 field of knowledge. In such cases it is rather the bounden duty of those who are 

 working out the material to discover characteristics by which the recognition of the 

 species is rendered possible, and this I believe I have achieved. Whoever keeps in 

 view all the points taken into consideration in the description, the structure of the 

 tentacles, of the septa, of the oral disk, of the circular muscle, &c., should find no 

 difficulty or doubt in identifying a form with a living species, taking for granted that he 

 has gained a correspondingly accurate anatomical knowledge of the latter. 



In conclusion, let me add a few words as to the state of preservation in which the 

 material for investigation was handed over to me. As all naturalists who have had 

 much to do with Actiniae know from personal experience, the animals are difficult to 

 preserve, and require special attention in putting up. As such attention could not be 

 devoted to them in the Challenger expedition, many of the Actiniae did not fulfil the 

 demands made by any kind of accurate histological investigation. I regret especially 

 that many of the specimens had been first placed in chromic acid or chromate of potash, 

 and then in alcohol. These were so dry and friable that they fell asunder like tinder 

 under the slightest pressure ; methodical dissection was therefore impossible, especially 

 as even letting them lie for some time in water did not restore flexibility to the body. 

 Preservation in chromic acid and chromate of potash must therefore be avoided, as it 

 offers no advantages for histological investigation. 



In many of the Actiniae, hardened in alcohol, the inner parts were likewise macerated, 

 perhaps because a large number had been placed in too small a quantity of alcohol, or 

 because dilute alcohol had been used. Anyone^coUecting Actiniae for examination ought 

 to attend to the following points. In the first place, it is advisable to keep the animals 

 separate till they are completely hardened, in order to prevent them from being flattened 

 while soft by pressing against each other. If this be not done, not only the form 

 but the sculpture of the surface suffers, which was often the case in the Challenger 

 material. In the second place, it is advisable to syringe the inside of the animal with 

 alcohol, placing the nozzle of the syringe through the mouth, or through a hole made in the 

 w^all or the pedal disk. On the other hand, cutting or even halving of the Hving 

 animal is to be objected to, as in that case it is impossible to avoid the destruction 

 of many of the septa, and the parts wiU be displaced much more than in the ordinary 

 contraction of the animal. 



In order to fulfil all requirements exactly, the Actinia before being preserved should 

 be subjected to a process which paralyses the muscles, such as has been previously 

 described by my brother and myself This, however, requires more time and care than 

 can usually be bestowed by the collector on a single object. 



