414 THE MICROSCOPE. 



liowever, do enter the chamber ; occasionally, but veiy rarely, one of 

 the loose bodies may be seen to escape from within, and get into the 

 outer current, it is then carried about until it becomes adherent to the 

 side of the frond. 



With regard to the propagation of the 0. Lunula, we have never 

 seen any thing like conjugation ; but we have repeatedly seen what we 

 shall now describe — increase by self-division. 



Observe the diagram D ; but for the moment suppose the two 

 halves of the frond, represented as separate, to just overlap each other. 

 Having watched for some time, the one half may be seen to remain 

 passive ; the other has a motion from side to side, as if moving on an 

 axis at the point of juncture : the separation then becomes more and 

 more evident, the motion more active, until at last with a jerk one 

 segment leaves the other, and they are seen as drawn. It will be ob- 

 served, that in each segment the endochrome has already a waist ; but 

 there is only one chamber, which is the one belonging to the one 

 extremity of the original entire frond. The globular circulation, for 

 some hours previous to subdivision, and for some /e?« hours afterwards, 

 runs quite round the obtuse end of tlie endochrome — as, by almost 

 imperceptible degrees ; from the end of the endochrome symptoms of 

 an elongation of the membrano.us sac appear, giving a semi-lunar sort 

 of chamber ; this, as the endochrome elongates, becomes more defined, 

 until it has the form and outline of the chamber at the perfect ex- 

 tremity. The obtuse end — 6 of the frond is at the same time elon- 

 gating and contracting : these processes go on j in about five hoxrrs 

 from the division of the one segment from the other, the appearance 

 of each half is that of a nearly perfect specimen, the chamber at the 

 new end is complete, the globular circulation exterior to it becomes 

 affected by the circulation from within the said charnber ; and, in a few 

 hours more, some of the free bodies descend, become exposed to, and 

 tossed about in the eddies of the chamber, and the frond, under a l-6th 



power, shows itself in all its full beautiful construction. 

 IV /{ E is a diagram of one end of a C. didymotocum, in which 



I i®^Pl__J ^^ same process was noticed. 



j (i^^P^ ; The .£'Mas<?'M??ii)irfcZto is well worthy of attention, as 



\j/ \ well as many other species, the Xanthidium Fenium, 



-> Bocidium, &o. The Arthrodesmus Incus has a very 



beautiful hyaline membrane stretching from point to 

 point, cut at the edges, something like the Micrasteria. This is im- 

 perfectly shown in fig. 196. 



The Mode of Finding and Taking Desmidacex. — As the difficulty of 



