ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 1003 



The primary nucleus, after taking on a sinuous shape, breaks up 

 and is absorbed during the abovo processes ; but the sinuous condition 

 lasts longer in P. caudatum than in the other forms. 



The author points out that the Ciliata and the Acineta3 are the 

 only organisms in which the nucleus and the nucleolus are so 

 completely distinct from one another ; and this dualism corresponds 

 to a physiological division of labour. Whereas in higher forms the 

 nucleus appears to be the active agent in fertilization, in the Ciliata 

 this function is localized in the nucleolus only, which thus represents 

 an hermaphrodite sexual apparatus. In a state of rest the nucleolus 

 is of small size, but at sexual maturity it undergoes a considerable 

 development, and passes through a series of transformations, recalling 

 fertilization in higher forms. There is an elimination of useless 

 material, and a differentiation into a fertilizing element and an 

 element to be fertilized; the former passing from one conjugating 

 individual to the other ; finally, by a fusion of these two elements a 

 mixed nucleus results, like that of a fertilized egg. The phenomena 

 taking place previously to tbe exchange serve only as a preparation 

 for tbe sexual act ; those that follow re-establish the dual nuclear 

 character, peculiar to the Ciliata. 



Zoocytium or Gelatinous Matrix of Ophridium versatile.* — Prof. 

 A. Harker has studied the gelatinous matrix of the organism upon 

 which the infusorium is found. The apparently spheroidal mass is 

 not solid, but forms an irregular hollow spheroid, the hollow usually 

 containing a large bubble of gas. In perfectly fresh slices of the 

 colony, under a power of 300 diameters and upwards, a large number 

 of unbranched threads, regularly divided by septa, are invariably to 

 be found, and on one occasion one of these tbreads was found in active 

 motion, suggesting a filamentous alga allied to Oscillatoria. 



The gelatinous mass associated with Oplirydium is of a very 

 obstinate character, and resists the action of almost any reagents but 

 strong sulphuric acid. After boiling in distilled water for half an 

 hour the gelatinous character is almost unaltered, and only after pro- 

 longed boiling in weak potassium hydroxide could the solution of the 

 jelly be obtained. After some hours' boiling, and subsequent treat- 

 ment with weak acetic acid to get rid of the carbonate of lime (whole 

 minute crystals are distributed throughout the mass), the residue, a 

 fiocculent mass, is found to consist entirely of the threads before 

 mentioned. These do not change colour on the addition of strong 

 nitric acid ; nor, again, do they give satisfactorily the celluloid 

 reaction with iodine and sulphuric acid. Their nature remains an 

 open question. 



The author adds some further notes on the animal. When liodit 

 is allowed to fall only on part of the colony, all the animals in a 

 very short time congregate to that part of the zoocytium, and on the 

 whole being freely exposed again to light they partially spread them- 

 selves over the surface, though a majority leave the matrix altogether. 

 In tanks they showed no disposition to form new colonies as described 



* Rep. 55th Meeting (1885) Brit. Assoc. Adv. Sci., 1886, pp. 1074-5. 



