208 
NOTES AND MEMOKANDA. 
the microscope as a polariscope is also specially advantageous for the 
study of small macled crystals of a structure more or less com- 
plicated and rich in interfacings, which only become visible with 
polarized light. With the eye-piece in place, these crystals can be 
examined with parallel light, and their peculiarities of structure and 
other points taken note of. The plates most suitable for examination 
can then be placed exactly in the centre of two crossed threads in the 
eye-piece, and on removing the latter, they can be examined with 
convergent polarized light. By this simple method the extremely 
complicated crystals of Phillipsite have been observed, also of 
Silesian Sirgwitz, which are only diaphanous when reduced to the 
thinnest plates. The small crystals of Tridymite were by these 
means shown by the author not to be hexagonal, as was considered 
from its pseudo-hexagonal form, with one optic axis, but biaxial — 
the two hyperbolas being plainly seen.* 
Quehett Microscopical Club. — Professor Huxley, P.K.S., has been 
elected to the office of President of this club for the ensuing session. 
Stromatopora as distinguished from Millepora. — Dr. Dawson, F.E.S., 
of Montreal, writes to the ‘Annals of Nat. Hist.’ (July) that the 
April number, containing Mr. Carter’s paper, “ Identity in Structure 
of Millepora alcicornis and Stromatoporaf reached him not long after 
the completion of a series of careful microscopic studies of the 
Stromatoporce and allied forms which abound in all the American 
limestone formations, and had arrived at the conclusion that these 
fossils appertain to the group of Ehizopods. After reading the 
paper, he re-examined the specimens of Millepora, but with the 
result of failing to find any indications whatever of the affinities 
asserted by Mr. Carter ; and he gives the grounds for disputing what 
he terms “ the somewhat extraordinary identification of two classes of 
organisms which scarcely resemble each other in anything except in 
being calcareous and porous.” 
Dr. Dawson mentions that having in his possession at present a 
considerable number of duplicate specimens of StroTnatopora, in such 
a state of preservation as to show under the microscope their actual 
structure, he will be happy to send by post chippings of these 
specimens to any naturalists desirous of studying them and of com- 
paring them with such organisms as Loftusia on the one hand or Eozoon 
on the other, with both of which the Stromatoporce have decided 
affinities. 
Professor Schwann’s Jubilee . — The fortieth anniversary of the 
professoriate of the co-author with Schleiden of the “ Cell theory,” 
and author of ‘ Microscopical Investigations on the Identity in the 
Structure and Growth of Animals and Plants,” was celebrated at 
Liege on June 23. The celebration included a laudatory oration of 
the Professor, the presentation of addresses from learned bodies 
throughout Europe, and of an album of living biologists, the unveiling 
of a bust, and, lastly, a banquet. Mr. F. M. Balfour, of Cambridge, 
represented England. 
* ‘ Bulletin de la Socie'tc Beige dc Microscopie,’ vol. iv. p. 177. 
