1887.] MICROSCOPICAL JOURNAL. 209 
Gage, second vice president; Professor T. J. Burrill, secretary; Dr. S. M. 
Mosgrove, treasurer; C. C. Mellor, Dr. Seaman, and Dr. Maudeville, exec- 
utive committee. 
The soiree was a grand success, with 123 microscopes in position, and 
over 3,000 people to enjoy them. It took over an hour to make the rounds. 
Among the specimens we mention the following :--Dr. S. M. Mosgrove, 
sections of a normal and a deseased lung, showing most clearly the bron- 
chial tubes and artery in the former as they are ina healthy babe’s organ, and 
in the latter as they are in the first stage of consumption. C. C. Mellor, 
infusoria and other inhabitants of an east end pond. Professor James H. 
Logan, living embryos of snails and infusoria from Pittsburgh water. Dr. 
Depuy, a longitudinal section of a human tooth, 5,455 part of an inch thick. 
Dr. Geo. E. Fell, letter O occupying space of one millionth part of an inch, 
magnified 3,200 times; also micrometric scales of from 5,000 to 12,000 
lines to the inch. Dr. Edward H. Small, the proboscis of a mosquito. 
Professor C. M. Vorce, skin of shark and jaw of leech. Bausch and Lomb, 
a number of the finest microscopes made in this country, and selected slides. 
Professor S. H. Gage, the muscular fibres of the mouse. Dr. Frank 
McDonald, micro-photographic slides of the Lord’s Prayer, and the picture 
of ‘ Pharoah’s Horses,’ both smaller than a pin’s head to the naked eye. 
The Microscope’s Laboratory; bacilli and embryonic subjects under six 
microscopes. Miss Mary A. Spenk, section of lung tissue and other objects. 
Dr. Frank L. James, extremely beautiful salicin crystals polarized. Dr. W. 
S. Bell, hooked wing of a hive bee. Dr. T. L. Hazzard, trzchina spiralis 
obtained from a local case. C.G. Milnor, diamond beetle and diatoms. 
George H. Clapp, eye-spot on wing of Luna moth and gold-plated diatoms. 
—WNat. Druggist. 
On the early history of the foot in Prosobranch gasteropods.* 
By HENRY LESLIE OSBORN. 
The literature of animal morphology is beccming more and more devoted 
to the subject of organogeny. The study of the development of organs is 
throwing much light on the story of their origin, the origin of species as 
well. The testimony of authors on gasteropod morphology prior to 1886 is 
to the effect that the foot throughout the group arises as a median elevation 
of the ectoderm upon the ventral surface behind the blastopore. Among 
the various writers who have given expression to this view are Carpenter, 
Bobretzky, Koren, Butschli, Salensky, Rabl, Balfour, and others, and their 
researches have extended to Fusus, Nassa, Natica, Cytherea, Trochus, 
Vermetus, and Paludina. ‘heir reports leave little doubt of their obser- 
vations on this point. 
MacMurrick, in a paper in 1886 on the development of Prosobranchs, figures 
but does not describe the first appearance of the foot in /w/guwr not as a median 
but as a paired structure. 
In studies in 1884 upon Fasctolaréa and Fulgur I observed and figured the 
first stages in the development of the foot. In both cases it arises as a pair 
of entirely independent elevations in the ectoderm behind the velum and 
blastopore on the ventral surface. Sections show them filled with meso- 
derm, the beginnings of the musculature, and the nervous system of the foot 
arises as two independent parts later united. It is very early that the two 
separate mounds coalesce to form the single median structure which persists 
as the peculiar form of foot. 
* Abstract of paper read before Biological Section of the A. A. A. S. in New York. 
