SCIENCE-GOSSIP. 



59 



again, with an empty pellet organ hard at work at 

 a new brick " ( 9 ). 



It will of course be clear, and is fully known to 

 every observer, that it must 

 be a matter of difficulty to see 

 distinctly what are the details 

 of this bricklaying, effected, 

 as it is, so rapidly. The 

 prime elements of success are 

 sharpness of definition, with 

 sufficient magnification, and 

 ample room for the activities 

 of the rotifer. 



With plenty of vigorous 

 specimens in full activity, and 

 by happy incidence, one well- 

 placed and building, taking a 

 240 mm. objective, we may 

 commence with the initial 

 magnification of the lens 

 (105 times), and we may go 

 on to 250 or more diameters 

 without change of focus or 

 disturbance of the object ; 



and by patience and repeated observation, we 

 may at last observe all the simple details of the 

 placing of 

 the brick. 



Judge Bed- 

 well made 

 the observa- 

 tion that a 

 small pim- 

 ple-like pro- 

 tuberance 

 armed with 

 setae and 

 lying be- 

 tween two 

 hooks, on the 

 opposite side 

 of the cup 

 in which the 

 brick is 

 made, pos- 

 sibly deter- 

 m i n e the 

 place in 

 which the 

 brick is to 

 bedeposited; 

 for ' ' when 

 the pellet is 

 ready the an- 

 imal turns 

 round and de- 

 posits it at 



the spot with which this pimple . . . was in contact 

 at the moment before the animal began to turn " ( 10 ). 



Fig. 2 — M. ringens, showing the ciliated 

 lobes, the chin (ch), the pellet in its mold (pm) 

 and antennae (an). 



(Copied by Dr. Dallinger from figure by 

 Dr. Hudson.) 



(Drawn from nature by Dr. Dallin 



This is undoubtedly true ; in the cases observed 

 by him it may have been always true, but in the 

 many observations made through two summers I 

 found that it was never so 

 with the first brick of a new 

 ring, but with the exception 

 of three instances was always 

 the case with every other 

 pellet of the ring. What 

 happened is shown in fig. 3. 

 The brick was ready, being 

 always formed in from three 

 to four minutes, then the 

 rotifer twisted swiftly round 

 about half the circumference 

 of her tube, pressed the side 

 of her body against the side 

 of the tube she had just 

 turned herself from, arched 

 her body over, laid her an- 

 tennae parallel with each other 

 and near enough to each other 

 to form a sort of double rail 

 or frame, down which the 

 pellet could roll or slide, and guiding it to the exact 

 spot to which it was destined to go. Then with 



the end of 

 her " chin " 

 she pressed 

 it into posi- 

 tion, much 

 as, with a 

 finger, we 

 may press 

 an electric 

 knob, and 

 then i n - 

 stantly rose, 

 mostly turn- 

 ed rapidly to 

 its former 

 position, and 

 again pro- 

 ceeded to the 

 construction 

 of another 

 pellet. 



When we 

 remem ber 

 that the dot 

 of an " i" in 

 this type will 

 probably 

 more than 

 represent the 

 superficial 

 area occu- 

 pied by the organism, all these refinements of 

 operation must surely awake interest in the mind, 



D. 2 



