400 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
elucidated in green, brown, and red alge, yet the mass of facts thus 
far obtamed presents an impressive picture of the essential identity 
of reproductive processes in these plants with those found in the 
cormophytes. Perhaps the most interesting pomt noted in making 
such a comparison is the fact that the type of life cycle among alge 
that corresponds most closely with that of a higher plant, such as an 
archegoniate, is the type found in several genera of the brown 
alge. The fact may be recalled here also that it was to the gamet- 
angia of this group that Davis (1903) finally turned im his search 
for a prototype of sexual reproductive organs of the bryophytes. 
VII.— SEXUALITY, CHROMOSOME HISTORY AND ALTERNATION IN THE 
FUNGI, 1820. 
In this group of parasitic or saprophytic thallophytes we shall 
find as great a variety in the type of reproductive process as in their 
mode of nutrition at the expense of the hosts beset by them. At 
the beginning of last century fungi were commonly supposed to arise 
spontaneously ‘‘out of the superfluous moisture of the earth and 
rotten wood.” 
Observations had been made long before this, it is true, sufficient 
to render improbable the then common belief in the spontaneous 
generation of the fungi. Thus Micheli (1729) had raised a fungus 
mycelium from spores. Ehrenberg (1820) did the same and also 
saw the conjugation of Sporodinia. Du Trochet (1834) proved that 
the mushroom arises from threads of the mycelium in the soil. 
The spontaneous generation of even the simplest of these parasitic 
or saprophytic thallophytes—the bacteria—had been denied by 
Leeuwenhoek at the end of the seventeenth century. In one of his 
numerous letters to the Royal Society he denies the spontaneous 
origin of the animalcule or bacteria which he found in the mouth. 
These he found present even in the mouths of ladies who cleaned 
their teeth carefully. He insists that these organisms are like those he 
obtained from pools of water, and then goes on to say, I a para- 
graph that reads like a modern health commissioner’s report: 
Now, when people wash their beer mugs and drinking cups in the water from ponds 
and streams, who can tell how many of these animalculze may stick to the sides of 
the glass and thus get into the mouth. 
_ The hazy or bizarre beliefs concerning the occurrence and the mode 
of reproduction in the fungi, current at the middle of last century, 
were dispelled by the studies of a group of able investigators early 
in the second half of the century. First came the splendid work of 
the brothers Tulasne (1847-1854) on the smuts and rusts, and their 
discovery of the odgonium of Peronospora. Pringsheim, in 1857, 
studied the sequence in development of the zoosporangia and odgonia 
