229 
Rickett.—Fertilization in Sphaerocarpos . 
In Sphagnum sub secundum , according to Bryan (1920), feitilization 
is replaced, at least in some cases, by a fusion of the ventral canal cell 
and egg. The possibility that a process of this type may be widespread 
among the Bryophyta makes it all the more desirable that the complete 
history of fertilization be followed in a number of forms. 
Material and Methods. 
The account that follows is based on a study of Sphaerocarpos 
Donnellii Aust. The plants used were grown on soil in three-inch pots, 
which were kept in Wardian cases in the greenhouses. . Most of the cultures 
originated in single sporelings or in single plants isolated from larger 
cultures. Cultures of each sex were thus kept separate until it was desirable 
to bring about fertilization.- Male and female plants were then trans¬ 
planted to the same pot. After about a week they had become firmly 
attached and were flourishing in the new soil. By flooding these mixed 
cultures with sterilized distilled water, the plants having been kept sub¬ 
merged about fifteen minutes, numerous sporophytes were obtained. The 
sporophytes first became visible under a hand-lens as small, spheiical, 
whitish bodies in the bases of the older involucres. The time necessary for 
them to attain this development varies from two to eight weeks from the 
time of flooding. 
The fixing fluid that gave the best results was made accoiding to 
Flemming’s medium formula, modified by the addition of 3 per cent, 
urea crystals. Satisfactory preparations were obtained by using only 
the most healthy cultures, by fixing during the cooler seasons of the year, 
and by taking special precautions in dehydration and in paraffin infiltration. 
To obtain a series of stages of fertilization in progress, plants fiom 
cultures that had been flooded were removed and fixed every few hours 
after flooding. Several trial sets of fixations sufficed to work out the best 
technique, and to disclose the approximate time involved in the process oi 
fertilization. Four complete series were then made, covering periods from 
a few minutes to five days after flooding, at intervals of from two to four 
hours. These series were designated as A, B, C, and D. The account that 
follows is based on all four of these series, which after close examination 
proved to correspond very closely in all essentials. 
The fixing plants were embedded in paraffin in the usual way, and sec¬ 
tions were cut 7 n in thickness. The stain most used was the Flemming triple 
combination of safranin, gentian violet, and orange G. The contents of the 
venter of the archegonium showed a marked affinity for the stains, especially 
for the safranin; so that it was possible only to dip the slide in the safranin 
and then necessary to destain in acid alcohol. An immersion of about 
a minute in gentian violet gave good results. Substitution ot light green foi 
orange G did not give as clear preparations. Heidenhain’s iron-alum- 
