HICKS, ON MR. ARCHER’S PAPER ON ALG. 253 
tain forms requires much knowledge of the substance em- 
ployed, and some patience, as there are many interfering 
causes to combat. Of these the weather is by no means an 
inactive one, as it is frequently found almost impossible to 
obtain the above-named feathery crystals when the place in 
which crystallization takes place is cold and damp. When 
the temperature is low, and yet too dry, santonine will fre- 
quently assume the form of a uniform semi-transparent 
mass after fusion, showing no crystalline shape; yet the 
same portion will crystallize beautifully when again fused, 
interfermg means being employed. This is also the case 
with many other salts. 
I myself was long under the impression that it was merely 
the thickness of the salt which caused the various forma~ 
tions; but on closer inspection found that, though thickness 
certainly did influence the forms, I did not find it difficult to 
procure the same class of crystals with either thick or thin 
coverings of the fused salt by recalling the before-mentioned 
facts. 
Remarks on Mr. Arcuer’s Paper on Arce. By 
J. Braxton Hicks, M.D., F.R.S., F.L.S. -&c. 
Ir was with much pleasure I read Mr. Archer’s paper in 
your Journal of April, 1864, read before the Natural History 
Society of Dublin, inasmuch as it opens up a question of 
much interest in many points of view, but more particularly 
bearing deeply on the validity of the classification of the 
unicellular forms of vegetable life. And as he in many 
places refers to my observations on these growths set forth 
in former numbers of your Journal, I] may, perhaps, be 
allowed to occupy a further space on the same subject. 
The title and the whole of this paper, coming as it does 
from so able and indefatigable an observer, proves more than 
any remarks I could have made the very unsatisfactory 
condition in which our knowledge remains, and also the 
great difficulty (may I say impossibility?) of fixmg the 
separate species or genus to which the majority of the 
Palmellacez belong. 
When, after all Mr. Archer’s careful and earnest researches 
on the subject, the title of this paper is called an “‘ Endeavour 
to Identify the Palmoglea Macrococca of Kiitzing” with a 
plant which he (Mr. Archer) thinks is meant, but which, 
