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PROGRESS OF MICROSCOPICAL SCIENCE. 
The Structure of the Echinoids,—It seems that M. 8. Lovén has 
published at Stockholm an essay on the above subject, which is of 
some importance. It is illustrated by fifty-three plates, and is likely 
to be of interest not only to the naturalist, but also to the paleon- 
tologist. The ‘ American Naturalist’ (February) says that it is chiefly 
zoological in its character, the text and plates are mostly devoted to a 
discussion of the homologies of the shell of the sea-urchins, parti- 
cularly those forms related to extinct genera of Echinoids. Com- 
parisons are also instituted with the classes of Asteroids (star-fish) 
and Crinoids, which will, if we mistake not, be found of much use 
to paleontologists. Especial attention is devoted to certain organs 
called Spherides, grouped around the mouth of sea-urchins, for the 
discovery of which naturalists are indebted to Professor Lovén. 
But the most interesting portions of the work are the exquisite 
drawings illustrating the anatomy and distribution of the nervous 
system and the water system of vessels. We have here for the first 
time, clearly shown, the more intimate relations of these organs. The 
plates are abundant and beautifully executed, the lithographs rivalling 
in clearness and delicacy the best steel engravings. 
The Position of Sponges.—Professor A. Hyatt, who lately read a 
paper on this subject before the Boston Society of Natural History, 
stated that he considered they formed the type of a new sub-kingdom 
of animals. He treated at some length on their mode of development. 
The paper will be published in the Society’s ‘ Transactions.’ 
The Oscillatoria and Bacteria formed the subject of a recent paper 
before the Boston Natural History Society, by Professor W. G. Farlow. 
Development of Scleroderma verrucosum.—In the ‘Annales des 
Sciences’ (1876, p. 30) an important memoir is published on the 
above subject by M. N. Sorokine, which is thus well abstracted by 
the ‘Journal of Botany’ (January). It says that attention is first 
directed to the two states, thread-like and lash-like, of the mycelium, 
upon which no organs of fecundation were discovered. In a very 
early state the mycelium consists of a cushion of short interlaced 
dichotomous filaments, which afterwards become still more interlaced, 
so that it has somewhat of a spongy structure consisting of masses of 
interlacing fibres with frequent cavities. Fine branches are now given 
off from the filaments which direct themselves into the nearest cavity, 
and when there bifurcate at their extremity, one of the bifurcations 
twining round its fellow; this is the commencement of the hymenium, 
which increases quickly by the formation of other filaments from the 
original one, and the young plantule now consists of a great number 
of hymenial masses contained in a darker-coloured common envelope, 
the intervals between the former being occupied by filaments which 
give origin to the capillitium. The filaments of the capillitium become 
transversely partitioned, and some of the segments are thickened, while 
