THe Microscope. 315 
but as the mass remained quiet, I attributed this to the slight 
currents produced in the water by the cilia of Trichodina pediculus, 
several of which found a home on the body of the Hydra, one 
in particular seeming to take special delight in climbing back 
and forth over the aforesaid excrescences. 
Never having previously seen anything of the kind in connec- 
tion with Hydra, I thought it might be interesting to others, 
although it may be nothing unusual. 
If any reader has a plausible explanation of the occurrence I 
wish he would make it known. 
EDITORIAL. 
R HEITZMANN’S theory in regard to the reticulated 
character of certain biological structures, as exemplified in 
his interesting paper on “The so-called cells of the cornea,” 
published in the present number of THE Microscops, has the 
merit of originality, yet few readers will be inclined to ac- 
cept it to the exclusion of the cell doctrine which he opposes 
The latter is no longer a theory; the existence of the cell is so 
frequently demonstrated, and the belief in its presence in animal 
and vegetable tissues so firmly fixed, that there is little danger 
of its over-throw. All of Dr Heitzmann’s papers are well writ- 
ten, attractive in manner, and interesting in matter, while their 
author has the courage of his convictions. He is no coward. He 
makes the onslaught single-handed, and with the bravery of one 
who feels that being right he must go ahead. His self-imposed 
task appears to be a hopeless one, yet all that he writes is worth 
careful reading. 
There is no doubt that under certain conditions and at certain 
times a net-work is observable in both animal and vegetable 
protoplasm, but it is not constant. Dr Heitzmann claims that 
it is a permanent and a characteristic feature of at least all ani- 
mal protoplasm. Few histologists agree with him. Gibson, 
however, in his recent “ Text-book of Elementary Biology,” ap- 
pears to accept the theory. “In intimate structure,” he says, 
protoplasm “consists of a homogeneous portion or matrix in 
