98 COHN, ON NASSULA ELEGANS. 
exists apparently in a solid form (mixed with the protoplasm), 
but that during the slow decomposition of the tissues it is 
gradually dissolved in the water, to which it communicates 
a blue colour. Whence it happens that the water in which 
Oscillatorie decay assumes a violet or blue colour, and the 
paper upon which specimens of these plants have been dried, 
exhibits a deep-blue border. The same colourmg principle 
occurs, beyond doubt, in all the Infusoria which are distin- 
guished by their variegated colours, changing from blue to 
bright green and yellow, as in the odontophorous genera 
Nassula, Chilodon, Prorodon, and Chlamydodon. The only 
doubt which can arise with respect to the occurrence of 
phycochrom in these animals, is, whether it reaches their in- 
terior simply as the result of the digestion and assimilation 
of the Oscillatorize, which notoriously constitute the principal 
aliment of these genera, and fragments of which may usually 
be noticed in the cavity of the body, or whether, like the 
chlorophyll-vesicles of Lowodes bursaria, Spirostomum, or 
Vorticella viridis, &c., it is not formed, in part at least, 
within the animal, as a peculiar pigment. At present, I re- 
gard the former supposition as the more probable. However 
this may be, the masses of phycochrom are, after a time, re- 
moved, collecting themselves, in Nassula elegans, previous to 
their ejection, into large masses close to the anal region; 
constituting in fact the violet-coloured masses composed of 
numerous blue globules, noticed above as being contaimed in 
the posterior part of the animal. ‘That the blue globules are 
only drops of fluid phycochrom, is evident from the circum- 
stance that when a Nassula is allowed to liquefy, the globules 
suddenly coalesce into a blue fiuid, which immediately after- 
wards loses its colour. It is manifest that m this case the 
water penetrates from without into the interior of the animal, 
and that in this water the droplets of phycochrom are im- 
mediately dissolved. The ejection of the globules of phy- 
cochrom through the anus and their sudden decoloration in 
the water has already been figured and described by Ehren- 
berg. I can see no reason for assigning to these blue masses 
any function of a special kind in the nutritive system. Nor 
on the other hand do I agree with Stein in regarding them 
as fragments of Oscillatorie, considering rather that they 
represent fluid particles of phycochrom extracted from the 
Oscillatorie which have been devoured, and are in process of 
digestion. Their assemblage on the back of the animal does 
not seem to me to be a constant occurrence. 
Other poimts of interest in the organization of Nassula 
elegans are: the reel-like, funnel-shaped dental apparatus 
