PROTOZOAN FAUNA OF HAY INFUSIONS PAs 
produced. These data, though too meager to be conclusive, 
suggest that sterile water added to fresh hay may prove to be a 
better medium for the development of the protozoa enecysted on 
the hay. 
C. CONCLUSIONS 
Viewed in their entirety, these twenty-three infusions indicate 
that: (1) Ordinary hay added to tap water usually will not 
produce an infusion which is productive of a sufficient number of 
representative forms to make it profitable for a study of proto- 
zoan sequence. (2) Air, water, and hay are all sources from 
which the Protozoa are derived, and increase in importance in 
the order given. Of these three, however, air is practically a 
negligible factor in seeding infusions. 
III. RELATIVE NUMBER AND SEQUENCE OF REPRESENTATIVE PRO- 
TOZOAN FORMS IN HAY INFUSIONS 
A somewhat regular sequence of organisms in infusions of one 
kind or another attracted the attention of the early devotees of 
the simple microscope, as is shown, for example, by the following 
paragraph from a letter written in September, 1702, by an anony- 
mous person who was led by the writings of Leeuwenhoek to 
make such studies: 
In my observations of the Animalcula in Waters I have seen many of 
the same species in the several infusions, and even in Waters that have 
been exposed (especially at this time of the year) any time without any 
particular mixture, such as you find in the hollow of a Cabbage-leaf, or 
on the Dipsacus, etc., and I am confident that many of these are the 
same Creatures under different dresses. For I have noted such a regular 
process in them, and such a constant order of their appearance, that I 
am of opinion most of them are the product of the Spawn of some invis- 
ible Volatile Parents? 
Nearly a century and a half later Dujardin, from his experience 
with infusions, wrote: 
> Philosophical transactions, Royal Society, London, vol. 23, 284, 1703, p. 1366. 
This communication is accompanied by the first published figure of Paramaecium. 
From the description in the text, however, it is evident that the author at times 
confused Paramaecium and certain hypotrichous forms. These same figures are 
reproduced by Baker, in his treatises on the microscope. 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 12, NO. 2 
