Davis.— The Fertilization of Batrachospermnm. 51 
that he has satisfied the conditions (isolation of female plants 
and normal environment) necessary to answer the problem 
stated at the beginning of the paragraph, in the following 
manner. 
Some stones, upon which were female plants of B. Boryanum 
and B. coerulescens , carefully freed from antheridial specimens, 
were placed in large glass jars. The jars were fitted with 
covers having a few holes punched in them, and were then 
sunk in the brook in the same situations from which the 
plants were collected. The conditions as regards light and 
temperature of the water were therefore the same, for the 
prepared plants and those growing wild around them. The 
holes in the covers allowed a constant slow interchange of 
water, but the swiftness of the current was greatly abated ; in 
fact, the plants were growing in almost perfectly still water. 
Of course the chances of antherozoids being brought to the 
trichogynes by the currents of water were thus greatly 
diminished. Jars containing plants of each of the three species 
were placed in the stream in the middle of December, and 
were taken out at different times and examined, the last 
having been in the stream two and one-half months. The 
experiments give very positive data. In the first place the 
plants in the jars appeared perfectly healthy. Two to three 
centimetres of new growth were added to each branch. The 
habit was not materially different, except that in some cases 
the new branches were not so stout as the old growth, the 
tendency being to produce long thin structures rather than 
short thick ones. The colour of the plants remained the 
same, and the cells of the tissue did not differ in any marked 
manner from those of plants under normal conditions. 
An abundance of procarps were produced in the situations 
peculiar to each species, and seemingly in the usual quantity. 
Almost all the trichogynes of B. Boryanum and B. coerulescens 
were free from antherozoids, and in each case there was no 
indication of any tendency to produce fruit apogamously. 
The trichogynes did not wither, but remained attached to the 
procarps in the usual manner, so that as one examined 
