Vi 
Parasites on Alge. 
IKE most other subjects that take their turn in popularity as 
fields of research, this one is by no means so new as may 
readily be thought. There are few things in Nature that our ‘rude 
forefathers,” with their ruder appliances, did not grapple with after 
some fashion. The earliest mention of any fact that may be classed 
under this heading is probably the discovery of the so-called “ galls” 
in the well-known siphoneous Alga Vauchevia. They were described 
and figured by Vaucher (1) so long ago as 1803, and many observers 
since then have added to the list of species infested, and have 
described the parasites and their operations. Of these writers, 
Balbiani (2) has given the most exhaustive account. The parasite 
in this case is an animal, and is described in the earlier papers as 
Cyclops lupula, but Balbiani and others refer it more accurately to 
Notommata werneckti. Ina paper on the subject by Professor Oliver 
(3), the animal is given on the authority of the late Mr. Gosse as pro- 
bably Rotifer vulgaris. The parasite enters a lateral fertile branch at 
an early stage, and sets up hypertrophy, causing it to swell to four or 
five times its originalsize. These gallshave been frequently observed, 
as has been said, and an extensive literature has arisen on the subject, 
which will be found fully cited by Mr. A. W. Bennett (4), who gives 
from Benké the following list of species on which they have been 
observed :—V. vacemosa, dichotoma, clavata, caespitosa, geminata, uncinata, 
and tervestvis. Lister observed them on V, aveysa and V. dillwynt. 
It is extremely probable that a considerable number of animals 
make use of Alge as their hosts, as they do of land plants; but 
botanical literature, so far as I can discover, contains remarkably 
little about it. Miss Barton (5) has described malformations of the 
thallus of the common dulse, Rhodymenia palmata, caused by a copepod, 
Harpacticus chelifer, which inhabits the tissues and burrows in them 
during a stage of itsexistence. The same enthusiastic phycologist (6) 
has recently described two other similar cases, viz., gall-like structures 
on Desmavestia aculeata, also caused by a copepod (too immature for 
determination), and very remarkable malformations of Ascophyllum 
nodosum, caused by a nematode worm, Tylenchus fucicola. This worm, 
nearly related to the well-known “ wheat-eels,’ has been minutely 
described and beautifully figured by Dr. de Man (7). 
