493 
Protoplasm in Coenocytic Hyphae. 
My attention was first called to movement in hyphae in 
1890, while examining bacterial cultures on plates of nutrient 
gelatin which had been invaded by some Mould, afterwards 
ascertained to be Rhizopus nigricans. Some account of these 
early observations was given before the Indiana Academy 
of Sciences at the meeting in December of that year 1 , but 
nothing was recorded in print regarding the matter. The 
movement was so very striking, and in such very common 
objects, which had been favourite subjects of study by sys- 
tematists, morphologists and physiologists for a century or 
more, that I hesitated to believe that it was unknown to science. 
For a very long time the conditions under which the 
movement takes place were not recognized, and it was only 
seen at intervals, and then for so brief a space of time that 
serious study was impracticable. In course of time it was 
found out that the most important condition is a saturated, 
or nearly saturated, atmosphere, and all subsequent studies 
were made with the cultures covered so far as possible. 
Some time spent at the Botanical Institute at Bonn during 
the summer of 1896 enabled me to prosecute my inquiry 
into the facts, and also to satisfy myself that no record of 
them had yet been made. I take the opportunity to acknow- 
ledge the kindness of Professor Strasburger in placing the 
resources of his laboratory at my disposal, in providing 
additional apparatus for my work, and of both Professor 
Strasburger and Dr. Noll for helpful suggestions. 
The hyphae of the Mucoraceae after attaining a certain 
maturity, I have found, set up a movement of the protoplasm, 
in which nearly or apparently all the contents — that is, the 
cytoplasm, microsomes, food-bodies, nuclei, and vacuoles — 
participate. It is a streaming movement, such as a somewhat 
viscous, colourless liquid would produce in flowing through 
a pipe. There is sometimes an evident ectoplastic layer 
lining the cell-wall that does not take part in the movement, 
but often this is so thin that it is no longer visible, although 
one cannot suppose that it is ever entirely absent. All kinds 
1 Bot. Gaz. xvi, 36. 
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