12 NOCTILUCA MILIARIS. 



view of it, and it is an equally difficult task to mount it for obser- 

 vation, as most media have hitherto failed. At my suggestion, a 

 weak solution of mercuric bichloride has been tried but without 

 success. The inner membrane, as usual, wrinkled up, and the outer 

 distended itself, and finally burst. I believe, however, it has been 

 preserved in a shallow cell, with sea-water as a medium, contain- 

 ing just a trace of carbolic acid, but I have not heard whether this 

 has been satisfactory during a lengthened period. 



If iodine is added to the water, it is rapidly absorbed into the 

 system, the fibres and fibrils permeated by the brown colouring 

 matter standing out with great distinctness. Indigo was placed in 

 the water, but none of the colouring matter entered the body of 

 the Noctiluca, and the animal died in about an hour. Irregular 

 jerking movements took place, says Dr. Webb ; the mouth-like 

 aperture and parts round it became distorted, the motion of the 

 cilium and tentacle still continuing, general contraction took place, 

 and then followed the disintegration to which I have already 

 alluded. 



This process occupied about two hours, but let me add that 

 the nucleus was not involved in the operation. The nucleus is a 

 strongly refractive body of about one four hundred and sixtieth 

 part of an inch, situated in front of and above the gastric cavity, 

 and when treated with acetic acid assumes the appearance of a 

 hollow vesicle. If the body of the Noctiluca has been ruptured, 

 and nearly all the contents lost, the creature still lives in this 

 deformed condition, provided the nucleus is entire, and the central 

 parts are left together. And then, after a time, they acquire a new 

 investment, the rags of the old garment being contemptuously cast 

 off. Dr. Webb further states that he has found this nucleus en- 

 closed in a second membraneous envelope, with a granular yelk- 

 like fluid, which could be seen pouring out when the membrane 

 was ruptured. 



The earlier writers on the subject before us came to the con- 

 clusion that the mode of reproduction was most probably by sub- 

 division ; it remained, however, for Colonel Baddeley to throw 

 still further light on the subject by closer attention and more 

 searching investigation. And the result of his observations are 

 practically these : A division of the nucleus having taken place, it 



