ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
249 
arm, gave the usual characteristics of ringworm. The author concludes 
that Trichophyton is “ a fungus able to vary its form and activity 
according to the physical and chemical properties of the soil on which it 
grows.” As a saccharine medium has been found to be the most 
favourable soil, it follows that the animal skin is unsuitable; hence 
“ the ringworm fungus vegetates, but does not develope ” there. 
Behrens, W., Kossel, A., u. Schiepferdecker, P. — Das Mikroskop and 
die Methoden der mikroskopischeii Dntersuchung. Bd. I. Die Gewebe des 
menschlicben Kbrpers and ihre mikroskopische Untersacbang. (Tlie Microscope 
and the Methods of Microscopical Investigation. Vol. I. The Tissues of the 
Human Body and their Examination by the Microscope.) 
Braunschweig (Bruhn), 8vo, 1889, 315 pp., 193 figs. 
Boneval, K. — Noaveaa guide pratique de technique microscopique appliquee a 
I’Histologie et a I’Embryogenie. Suivi d’un formulaire indiquant la composition 
des reactifs employes en anatomie microscopique. (New Practical Guide of 
IVIicroscopical Technique applied to Histology and Embryology. Followed by 
formulae for the reagents employed in Histology.) 8vo, Paris, 1889, 21 figs. 
Davis, G. E. — Practical Microscopy. New ed., Philadelphia (Lippincott), 1889. 
Kamon y Cajal, S. — Manual de histologia normal y de tecnica micrografica. 
(Handbook of normal Histology and Microscopical Technique.) 
Valencia (Ostega), 4to, 1889, 692 pp., 203 figs. 
(2) Preparing: Objects. 
Mode of studying Free-swimming Larvae.* — Dr. G. C. J. Vosmaer 
recommends that free-swimming larvae should be put into a glass, the 
bottom o-f which is covered by a loose, thin sheet of collodium ; to this 
they attach themselves readily. The spot to which a larva is attached 
can be cut out under water whenever required. The collodium is trans- 
parent and easily cut with the larva. If it is desired to examine the base, 
the collodium may easily be dissolved. The preservative fluid recom- 
mended is that which Kleinenberg used for Lopadorhynchus ; this gives 
by far the best results, cilia, for example, being hardly shorter than in 
the living animal. 
Examination of Renal Organ of Prosobranch Gastropoda.f — M. R. 
Perrier has used three methods in examining the renal organs of Proso- 
branch Gastropods. The examination of living tissues, teasings, and 
serial sections have been the methods employed. The great difficulty 
to overcome has been the extreme alterability of the tissues, and the 
delicacy of the renal cells has been noticed by all observers. Under 
the influence of whatever reagents, the epithelium becomes completely 
destroyed unless sufficient precautions are taken. Owing to the changes 
which are continually taking place it is necessary to at once arrest the 
secretion. Ordinary fixing reagents, and particularly osmic acid, are of 
no use for this purpose ; indeed, they seem to make the secretion more 
active. The best results have been obtained with acetic or picric acid, 
or, still better, a mixture of the two ; picro-sulphuric acid has also been 
of use. The organ must be cut out of the body as rapidly as possible, 
plunged for one or two minutes into a 1 per cent, solution of osmic acid, 
w'ashed rapidly, and left for some hours in a mixture of picric and acetic 
acids. It must then be put in 70 per cent, alcohol for as long a period 
* Tijdschr. Nederl. Dierk. Ver., ii. (1889) p. 289. 
t Ann. Sci. Nat. Zool., vii. (1889) pp. 71-9. 
