14 Development of the Male Prothallium, etc. []anuary,. 
theridia were formed, it was an easy matter to trace the develop-. 
ment back, but it was impossible to determine just where it 
began. The process was as follows: After the branch in which 
the antheridium was to be formed had attained sufficient size, 
there was a concentration of protoplasm at this point (Fig. 18), a 
cavity being gradually formed, at first indistinct, but finally 
assuming a nearly regular oval shape (Fig. 19). This mass of 
protoplasm soon breaks up into small round bodies that are dis- 
charged as antherozoids. The first antheridia are formed singly, 
but later (Fig. 19) two or three are formed almost simultaneously 
at the end of a single branch. When the antherozoids are ma- 
ture, the cells surrounding the interior cavity of the antheridium 
separate, leaving an opening by which they escape. Usually the 
whole mass of antherozoids is discharged in a few minutes, but 
sometimes the discharge is more gradual. Each antherezoid is 
enclosed in, and lies coiled up within,a membrane. After resting 
for a few moments this sac bursts, freeing the enclosed anthero- 
zoid, which immediately swims rapidly away with a peculiar un- 
dulatory movement due to its spiral form. The most noticeable 
thing about them is their great size, for while most antherozoids 
are so minute as to look like mere specks, even when a high 
power is employed, these are readily studied with an ordinary % 
objective. They are quickly killed by the application of iodine 
by means of which the cilia are made rigid, standing out in all 
directions from the thicker end of the antherozoid, and plainly 
visible with the low power. The body is long and slender, taper- 
ing to a point at one end and bearing the remains of the envelop- 
ing sac in the inner side. The body is contracted, becoming 
shorter and blunter after iodine is applied. 
In germinating the spores, the only precaution necessary is to 
keep the atmosphere around them moderately damp. In making — 
the foregoing observations, this was done by sowing the spores 
on damp earth in unglazed earthen saucers which were placed 
under bell jars. By giving water every two or three days no- 
difficulty was experienced in keeping the prothallia in a healthy 
condition. 
EXPLANATION OF PLATE I. 
Fic. 1.—Two spores, one with the elaters coiled around it, the other with the elater> 
expande 
Fics, 2 and 3. —Germinating spores on sich 
* 4,5 and 6.—G g spores o aien 34, showing variations in mode of 
ion 
PES OSS ee ee ae eo eee ea 
