PROGRESS OF MICROSCOPICAL SCIENCE. 255 
of the late Professor C. M. Wetherill that the grains of sand are 
shaped like dumb-bells was referred to with a doubt of its correct- 
nes. The part which the scales of mica play can only be shown by 
the examination under a microscope of carefully ground sections of 
the stone, which might perhaps be prepared for cutting by solutions 
of soluble glass. On concluding his remarks, Professor Blake was 
followed by Professor Leidy, who stated that he had examined Itacolu- 
mite microscopically without being able to detect anything like the 
dumb-bell structure described by Dr. Wetherill. He supposed that 
the intermingling of grains, differing in translucency and colour, gave 
rise to the impression of a dumb-bell arrangement. Thus a pair of 
adherent translucent grains surrounded with smaller coloured ones 
would give rise to such an impression. 
Circulation in a Fungus.—Mr. A. Lister recently exhibited a very 
interesting microscopic object at the Linnean Society. It was a bit of 
a lowly organized fungus known as Oldhamia utricularis, and there 
was seen to be a definite current running along spaces which had 
certainly the appearance of vessels. This current was of a clearish 
liquid, having numerous corpuscular elements in it. It was kept up 
for a considerable space of time. Mr. Lister promised to exhibit it at 
the Royal Microscopical Society, but unfortunately the approach of 
cold weather absolutely destroyed it. 
Botanischer Jahresbericht—We learn that the first part of the third 
volume of this admirable work has appeared, and we take this oppor- 
tunity of recording the fact. We received the two earlier volumes 
some years since, and we have found them very valuable résumés of 
the work done in previous years, not only in general botany, but in 
physiological and microscopical work. 
The Reproduction of Ulothrix zonata.—An important memoir of 
considerable length has been published on this subject in ‘ Prings- 
heim’s Jahrbiicher’ (vol. x. part 4), by Dr. Arnold Dodel, and there 
is an abstract of it as follows in ‘Silliman’s Journal’ for February. 
The genus Ulothrix belongs to the order Zoosporez, in which the re- 
production takes place by means of the macrozoospores and micro- 
zoospores, the former having four cilia and one germinative spot (the 
name given to the reddish-coloured dot found on one side), the latter 
having only two. The former bodies have for some time been con- 
sidered non-sexual, while the latter have been supposed to represent 
sexual organs which by their union form a body with four cilia, and 
distinguished from the macrozoospores by having two germinative 
spots instead of one. This body, which is called the zygospore, cor-_ 
responds to the organ of the same name in the Desmidez and Con- 
jugate proper. Dodel confirms the views of Areschoug, Cramer, and 
others, that the macrozoospores do not conjugate, but, after losing 
their cilia and coming to rest, grow at once into a new plant. He also 
agrees, in the main, with Areschoug as to the conjugation of the 
microzoospores, aud besides has been able to give a more exact ac- 
count of what becomes of the zygospores. He finds that they remain 
for a considerable time unchanged, and finally divide into a number 
VOL. XVII. U 
