ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 253 



serum has been previously heated to 55° for 20 minutes. It is then 

 inoculated with the material to be examined ; from this first tube, a 

 second is inoculated, from the second a third, and often a fourth from 

 the third. After the inoculations, the contents are poured into the 

 larger half of a Petri's capsule, and covered with the small part turned 

 upside down ; the pair is then covered With a still larger half (fig. 62). 



[^j^^^^^^^^^ 



Cultivation 

 media 



Fig. 62. 



After ;> or 4 days' incubation, one of the halves is removed and any 

 colonies descried are fished out by means of a glass pipette. 



When dealing with very slowly growing anaerobes, especially in 

 intestinal contents, it is advisable to add 3 p.c. lactose as well as the 

 foregoing constituents. 



When the microbes are isolated it is quite easy to cultivate them in 

 a liquid medium. 



(2) Preparing- Objects. 



Fixation Methods and Elimination of Artefacts.* — G. Rubenthale 

 has obtained satisfactorv results towards the eliminating of artefacts 

 produced by existing fixation methods, by endeavouring to minimise the 

 shock produced on the living tissue by the reagent, and, besides in- 

 sisting on the principles of isotony and isothermy, the author advocates 

 diminishing the sensibility of the tissne by ansesthesia, and a slow appli- 

 cation of the fixation reagent, commencing with weak solutions and 

 gradually increasing them until the desired result is obtained. Isotony 

 is attained by placing the specimen in the medium to which it natu- 

 rally belongs — muscle into blood-serum, nerve into cerebrospinal fluid, 

 embryonic tissue into amniotic fluid, etc. Anaesthesia is conferred by 

 immersing the tissues in solutions of hydrochlorate of cocaine or chloral 

 hydrate. These methods, however, increase the duration of the fixation 

 process, and to somewhat obviate this effect the author reduces the size 

 of the specimen. A detailed account is given of the technique employed. 



Studying Spirochseta Balbiani and Spirochasta Anodontse.f — 

 H. B. Fantham examined these two Spirochetal in their natural 

 environment as far as possible. When a style was present, the freshly 

 extracted structure was mounted in a drop of sea-water or fresh-water 

 in the cases of Ostrea and Anodonta respectively, and placed in a moist 

 chamber. The organisms were thus kept alive from 3 to G hours 

 while the style was examined in sections in the laboratory at a tempera- 

 ture above that normal to the animals. The fluid contents of the stylo 

 were pressed out and the still wet smear fixed with osmic acid vapour, 

 or hanging drops of the parasites in their natural medium were made 



* Zeitschr. wiss. Mikrosk., xxiv. (1907) p. 133. 



t Quart. Joum. Micr. Sci., lii. (1908) pp. 1-73 (: J . pis, and 11 figs, in text). 



