ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
417 
fixed to the medium. On potato tho growth was particularly luxuriant 
and quite typical, the cultivation having a characteristically dry 
appearance. In bouillon the miliary nodules soon appeared, and grew 
up into masses the size of a hazel-nut, the bouillon remaining clear. In 
milk, the ray fungus throve well, the albuminoids of the milk being 
apparently directly peptonized without previous coagulation. 
The authors found that the growth of the fungus was completely 
stopped at a temperature of 52° C. and that even 40° C. exerted an inhi- 
bitive action. 
The authors further observed that the fungus presented in their 
cultivation a cyclical polymorphism, that is, the Actinomyces filaments, 
at first distinguished by their dichotomous ramifications, eventually 
assumed, by continual subdividing transversely and longitudinally, the 
appearance of rodlets and cocci, from which again developed the long 
branched filaments. 
This variety of polymorphism was specially observable in potato 
cultivations, while in old cultivations real retrograde metamorphoses, 
e. g. club-shaped or spirilla forms, mucous degeneration, &c., were 
remarked. 
The authors regard the rosette form found in men and beasts as the 
expression of a parasitic adaptation to the animal body. 
Further experiments showed that in old cultivations the further 
development of the cultivation was inhibited in consequence of the 
accumulation of metabolic products. 
The results of the experiments on animals are reserved for a further 
communication. 
Apparatus for facilitating Inoculation from Koch’s Plates.* — 
Herr W. Prausnitz has devised an apparatus for facilitating the 
inoculation of particular colonies from Koch’s plates. 
It consists of a metal ring which is screwed on to the Microscope- 
tube. From one side projects a metal piece, in which is left a linear 
fissure for the insertion of a platinum plate. From the lower end of the 
plate is excised a triangular piece. The inoculating needle is made to 
rest in the angle of the platinum plate, its point being about 2 mm. from 
the colony. The apparatus is merely intended as a device for keeping 
the needle steady, so that the special micro-organisms only are 
removed, and uncontaminated either by the medium or by adjacent 
colonies. 
Picric and Chromic Acid for the rapid Preparation of Tissues for 
Classes in Histology, f — Mr. S. H. Gage remarks: — “The standard 
methods of hardening tissues and preparing them for sectioning require 
so great an expenditure of time that it is practically impossible for 
students in college and carrying on other university work to perform all 
the processes and to make any satisfactory progress in the limited time 
devoted to histology. Believing firmly that unless a student learns to take 
every individual step himself in histology, as in all other branches of sound 
learning, the great object is unattained, I have been experimenting for the 
* Centralbl. f. Bakteriol. u. Parasitenk., ix. (1891) pp. 128-9 (1 fig.), 
f Proc. Amer. Soc. Mier., 1890, pp. 120-2. 
