54 Tue Microscopr. 
cated completely and, on applying moisture, they would again 
rise from their dryness to perfect form and activity. A more 
careful experimentation, however, led to the more reasonable 
conclusion that a rotifer, deprived of moisture, is destroyed ; it 
was found that the drying up of the water containing the indi- 
vidual must be gradual in order to an apparent rising from its 
ashes ; that under such a condition a cyst was formed by a gel- 
atinous excretion from the animal’s body which was absolutely 
impervious, hermetically sealing up the rotifer, moisture and 
all; its activity nearly or quite ceased and it could resist sum- 
mer heat and drought or winter cold. It, in some way, was 
able to quickly free itself on the return of favorable conditions. 
In the same way Infusoria protect themselves when the 
ponds and streamlets disappear in summer; thus it is that they | 
are distributed as dust by winds, other natural means and acci- 
dents, so that every bit of water allowed to stand exposed to 
the air dust for a few days becomes the home of a few or many 
species. This protective encystment should not, however, be 
confounded with what has been called “duplicative” and 
‘‘ sporular” encystments in which the self imprisoned infusor- 
ian subdivides into two individual infusorians, similar to the 
original, or, into many sporular bodies which, after a longer or 
shorter resting stage develop into the adult form. Examples of 
protective and duplicative encystment will be referred to at 
some length below. 
In the spring of the year every forest pond and wayside 
pool swarms with Entomostraca, and among these Cyclops es- 
pecially bears the most bewildering number of short stalked 
vorticellids. I have thus far failed to satisfactorily identify 
them and have again and again given them up as an odd lot. 
One of this interesting collection I had, for some time, felt sure 
was a representative of the genus Rhabdostyla as defined by 
its proposer, W. S. Kent, but on further examination it was dis- 
covered that its short pedicle, instead,of being rigid, possessed a 
rudimentary muscle and was, consequently, flexible at the upper 
part, so it was not a RAabdostyla, nor did it appear to be a typ- 
ical Vorticella; here I rested. Since then Prof. G. Entz’s ae- 
count of FP. sertularium, Kent, under the title Spastostyla ser- 
tulariarum has been received and it helps to clear up matters, 
