874 MR. 8. LE M. MOORE'8 STUDIES 
amount of polymorphism such as has never before been described 
for any alga. 
Some further Remarks. 
From the foregoing statements it is to be gathered that there 
is a direct relation between the condition of the wall and the way 
in which the zoospores are set free. Should the wall break down 
at only one point, the rest of it retaining, or losing to but a slight 
extent, its original characteristics, the zoospores will escape at 
that point: in this case the inner portion of the wall is the first 
to become modified, otherwise the zoospores embedded therein 
would not be able to disengage themselves; and this also hap- 
pened with the zoosporangium iu which I saw the inwardly- 
diseharged ecenobium. The reverse holds good when zoospores 
or coenobia are discharged outwardly ; hereitis the outer portion 
of the wall which first undergoes degeneration. With reference 
to the difficulty of making out cilia in some states of the zoospo- 
rangium, it has already been mentioned that they are liable to drop 
off when the wall has undergone much degeneration, the patho- 
logieal ehange of the latter apparently involving also the cilia 
passing through it: we know that the same thing happens with 
Eudorina, Pandorina, &e., as a prelude to each phase of their 
history. 
Reference to methods of culture has been purposely delayed 
until now that details about the zoosporangial wall have been 
given. The great diffieulty in the observer’s way here, as with 
many other alge, is the extreme delicacy of organization— 
the rapidity of response to the action of unfavourable conditions 
as respects light, temperature, and above all of oxidation— which 
characterizes these plants. That I have been quite unable to 
cultivate Apiocystis in such a fashion as to allow of continuous 
observation will therefore scarcely excite surprise. The main 
reason for this failure is the readiness shown by the wall to break 
down—to lose its distinctively cellulose nature—upon the slightest 
occasion. This will usually happen in three or four days by 
simply bringing indoors the vessel in which the culture is going 
forward ; and mere removal of the Apiocystis to a watch-gluss acts 
prejudicially upon its health, even when the water is frequently 
changed ; as may hence be concluded, hanging-drop cultures are 
out of the question. When spcaking of externally-escaping 
coenobia, it was mentioned that such were never seen actually 
